제24회 유전체물성 심포지엄 제16회 강유전체 소자 소재...

제11차 강유전체 연합 심포지엄

제24회 유전체물성 심포지엄&

제16회 강유전체 소자/소재 워크숍

초 록 집

2015년 2월 1일~3일

무주리조트 (카니발 컬쳐 팰리스)

주최

강유전체연구회

주관

울산대학교 물리학과 BK21플러스사업단

후원

한국물리학회 응집물질물리 분과, KCMC, 넥스트론, 한맥전자

한국물리학회 응집물질물리 분과

http://www.kps.or.kr

KCMC

http://www.kcmc.biz

넥스트론

http://www.nextron.co.kr

한맥전자

http://hanmacco.com

Sponsors

초청의 말씀

안녕하십니까? 반갑습니다. 매년 새해가 밝아오면 무주에서 개최되는 강유전체 연합 심포지엄이 생각납니다. 올해도 산화물 유전체 분야를 연구하는 재료공학과 물리학 분야 연구자들이 만나서 연구 결과를 발표하고 함께 논의할 수 있는 즐거운 시간이 무주리조트 카니발 컬쳐 앙상블 홀에서 개최합니다. 특히, 올해는 2월 초에 강유전체 연합 심포지엄이 개최되기 때문에 참가하는 학생들과 연구자들이 덕유산 향적봉 행 곤돌라를 타고 보는 아름다운 경치와 함께 향적봉의 눈꽃 축제도 즐길 수 있으며 또한 무주리조트에서 스키를 즐길 수 있기를 기대됩니다. 본 학술대회는 국내 유전체 연구뿐만 아니라 다양한 기능성을 가지는 산화물 분야를 연구하는 물리학, 재료공학 분야의 기초 및 이론 연구와 함께 이 연구를 바탕으로 실질적으로 산업에 응용할 수 있는 응용연구 결과를 함께 논의할 수 있는 소중한 자리이며 또한 서로 자주 만나지 못하였던 연구자들이 서로 우정을 함께할 수 있는 기회가 될 것입니다. 강유전체 연합 심포지엄에 참가하는 모든 참가자들이 2015년 2월 무주리조트를 기억할 수 있는 추억이 남는 즐거운 시간이 되기를 기원합니다.

강유전체 연합 심포지엄 공동위원장 김 일원 (울산대학교) 이 재찬 (성균관대학교)

강유전체 연합 심포지엄 공지사항

- 1 -

심포지엄 조직위원회

■ 자문위원회

권숙일(서울대), 조성호(고려대), 장민수(부산대), 김종진(KAIST), 백성기(포항공대),

박광서(서강대), 정윤희(포항공대), 하조웅(INOSTEK), 박철홍(부산대)

■ 조직위원회

위원장 : 김일원(울산대), 이재찬(성균관대)

위 원 : 장현명(포항공대), 노태원(서울대), 황윤회(부산대), 김상수(창원대),

김명호(창원대), 윤종걸(수원대), 황철성(서울대), 김승현(브라운대)

■ 준비위원회

김일원(울산대), 신영한(울산대), 안창원(울산대), 석해진(울산대),

박효주(울산대 BK21플러스사업단)

■ 논문편집위원회

위원장 : 송태권(창원대)

위 원 : 강보수(한양대), 부상돈(전북대), 양호순(부산대), 이종숙(전남대),

장호원(서울대), 정대용(인하대), 조지영(GIST)


- 2 -

1. 장소 (학술발표) 무주리조트 카니발 컬쳐 팰리스 지하1층 앙상블 홀(Banquet) 무주리조트 카니발 컬쳐 팰리스 지하1층 심포니 홀(후원업체 홍보) 무주리조트 카니발 컬쳐 팰리스 지하1층 로비

2. 일시

2015. 2. 1.(일) 14:30 ~ 2. 3.(화) 12:003. 강연구분

특별강연 30분 (25분 발표 + 5분 질문)초청강연 20분 (15분 발표 + 5분 질문)학생강연 15분 (12분 발표 + 3분 질문)포스터발표 (1시간 30분)

4. 학회등록

사전등록기한 : 2015. 1. 5.(월) ※ 등록비 : (박사급이상 및 일반) 190,000원 (학생) 140,000원현장등록 : 등록비 외에 추가비용(10,000원) 부담 ※ 등록비 : (박사급이상 및 일반) 200,000원 (학생) 150,000원

5. 초록제출 및 논문투고

초록제출기한 : 2015. 1. 5.(월)Manuscript 제출기한 : 2015. 3. 5.(목)① 투고논문은 강유전체연합심포지엄 논문편집위원회 주관으로 한국물리학회의 JKPS 특별호의

규정에 따라 peer-review 후에 게재 될 예정입니다.② 논문투고 시 논문접수기간내에 JKPS의 본학회 관련 특별호 웹창에 직접 투고하시면 됩니다.③ 논문게재료는 저자부담입니다.④ 2011년 개정된 한국물리학회의 JKPS 특별호 발행지침에 의하여 동일 저자는 공동 저자를

포함하여 최대 2편까지 투고할 수 있습니다.6. Banquet

2015. 2. 2.(월) 오후 6시, 무주리조트 카니발 컬쳐 팰리스 지하1층 심포니 홀※ 동반자 참가비 무료

7. 편한복장으로 참석하십시오.

8. 문 의:

조직위원장 울산대학교 물리학과BK21플러스사업단 무주리조트(숙박 및 시설)울산대학교 김일원 교수전화: 052-259-2323 팩스: 010-2245-2023E-mail: [email protected]

행정직원 : 박효주전화: 052-259-1930 팩스: 010-8638-9655E-mail: [email protected]

전화: 063-320-6801~5 (행사진행 및 답사) 063-320-7617 (티롤호텔) 063-320-7830~4 (가족호텔-콘도)


- 3 -

무주리조트 찾아오시는 길

(주소: 전북 무주군 설천면 만선로 185)

※ 교통편 : (기차의 경우)

서울역 → 영동역 : 새마을 2시간 30분 소요대전역 → 영동역 : 새마을 30분 소요동대구 → 영동역 : 새마을 1시간 20분 소요부산역 → 영동역 : 새마을 2시간 30분 소요

→ 무주군 (버스 20분)

→ 무주리조트(택시 20분)

(셔틀(시외)버스 50분: 설천면 경유)

※ 참조: 무주리조트 홈페이지 (www.mdysresort.com)


- 4 -

무주리조트 안내도

(주소: 전북 무주군 설천면 만선로 185)

※ 참조: 무주리조트 홈페이지 (www.mdysresort.com)

■ 무주리조트 도착 후 학회 등록 전 추천 일정

① 무주리조트 도착 → 웰컴 센타에서 숙박 체크인 후 숙소로 이동

② 숙소에서 짐 정리 → 학회장소 이동 (카니발 컬쳐 팰리스)

③ 등록데스크에서 등록 후 학회 참석 (2015. 2. 1. 14:30 등록시작)

(카니발 컬쳐 팰리스 지하1층 앙상블 홀 앞)


- 5 -

학회장 안내도 (무주리조트 카니발 컬쳐 팰리스 지하1층)

2015년 2월 1일 저녁식사 장소 (만선하우스 3층, 만선한식당)


- 6 -

논문 투고관련 상세 안내

① 투고논문은 강유전체연합심포지엄 논문편집위원회 주관으로 한국물리학회의 JKPS 특별호의 규정에 따라 peer-review 후에 게재 될 예정입니다. (편집위원장 : 창원대 송태권)

※ 투고논문의 게재승인율은 70%이하 입니다.② 논문게재료는 저자부담입니다.③ 2011년 개정된 한국물리학회의 JKPS 특별호 발행지침에 의하여 동일 저자는 공동 저자를 포함하여 최

대 2편까지 투고할 수 있습니다.

■ 논문 투고 방법은 다음과 같습니다.

물리학회의 JKPS 특별호 웹창에서 직접 투고하여 주십시오.웹투고 창: http://jkps.kps.or.kr/home/journal/article/submission/submission_insert_form_first2009.asp?globalmenu=3&localmenu=2

제출 마감일 : 2015년 3월 5일 (목)

6개 분야로 나누어지며, 웹창 투고시 아래 코드번호 및 포스터 발표번호를 반드시 입력하여 주시기 바랍니다.

코드번호 : 01) Ferroelectric properties

02) Low dimensional and Nano Ferroelectrics

03) Emerging (or Functional) Ferroelectrics

04) Memory and high K Applications

05) Piezoelectric and Electro-optics

06) Energy materials

07) 기타

◾논문원고는 MS Word 또는 TeX으로 작성하시되, 유전체물성연구소 홈페이지 공지사항이나 물리

학회 JKPS 웹투고창에서 반드시 Template을 download 하셔서 양식에 맞추어 작성하여 주십시오.

◾분량 : PDF(출판 format)로 전환하였을 때 4페이지 정도

■ 논문 투고시 PACS번호(Home Page 참조) 및 Keyword는 반드시 알려주셔야 합니다.

■ 원고는 한국물리학회에서 발행하는 물리학 용어집을 참조하시어 작성하여 주시기 바랍니다.

■ 논문은 연구논문, 소논문, 해설 및 논평으로 구분되며, 연구논문, 소논문과 논평은 편집위원회에서 정한

심사과정을 거치고 수정지시와 채택여부는 편집위원회가 결정합니다.

1. 소논문은 논문의 수준이 연구논문과 비슷하고 본문을 절로 나누어 쓰지 않으며 인쇄하여 네 쪽을 넘지

않는 논문입니다.

2. 논평은 이미 게제된 논문에 대한 의견을 담으며 편집위원회의 심사를 통해 그 대상 논문의 저자에게 전

달되고 대상 논문의 저자는 논평에 대한 회답을 할 수 있습니다. 논평과 회답은 초록이 포함되지 않으

며, 각각 인쇄하여 한 쪽으로 제한합니다.

3. 해설은 편집위원회를 거쳐 편집위원장이 의뢰하는 것을 원칙으로 하며 기타의 해설은 편집위원회에서

정한 심사를 거칩니다.

■ 기타 논문작성에 관한 상세한 사항은 한국물리학회 논문투고규정[JKPS]을 참조하시기 바랍니다.

■ 게제된 논문에 대해서는 학회에서 정한 게재료를 지불하여야 합니다. (별쇄본 없음.)

제11차 강유전체 연합 심포지엄, 2015. 2. 1~3, 무주리조트

- 7 -

19:20 ~ 19:40 I5 Understanding Defects in Ferroelectrics and Their Application

세라믹기술원 이순일

19:40 ~ 20:00 I6 BiVO4 단결정의 Incommensurate Twin Domain Wall에 관한 연구

부산대학교 장민수

20:00 ~ 20:15 O1 Antiferroelectric HfxZr1-xO2 thin films for the energy-related applications

서울대학교 박민혁

20:15 ~ 20:30 O2 Structural properties of strained epitaxial PbVO3 (001) thin films

이화여자대학교 오설희

20:30 ~ 20:45 O3 Oxygen octahedral rotation angle of BiFeO3 films depending on structural modulation of SrRuO3 bottom electrode layer

GIST 이성수

Program

장소 : 카니발 컬쳐 팰리스 지하 1층 앙상블 홀

14:30 ~ 16:00 등록

16:00 ~ 16:10 개회

(좌장 : 전북대학교 부상돈)

16:10 ~ 16:40 P1Revisit of lead-free piezoelectric material systems for practical device applications

브라운대학교 김승현

16:40 ~ 17:00 I1Frequency and temperature dependence of incipient piezoelectricity

UNIST 조욱

17:00 ~ 17:20 I2Lead-free piezoelectric BiFeO3-BaTiO3 thick films

창원대학교 송태권

17:20 ~ 17:40 I3Practical applications of Bi0.5(Na,K)0.5TiO3-based lead-free piezoelectric ceramics

울산대학교 안창원

17:40 ~ 18:00 I4Piezoelectric micromachined ultrasonic transducer (pMUT) by granule spray in vacuum process (GSV)

재료연구소 류정호

18:00 ~ 19:20 저녁식사 (장소: 만선하우스 3층, 만선한식당)

(좌장 : 세종대학교 최택집)

2월 1일 (일요일)2월 1일 (일요일)

제11차 강유전체 연합 심포지엄. 2015. 2. 1~3, 무주리조트

- 8 -

장소 : 카니발 컬쳐 팰리스 지하 1층 앙상블 홀

08:00 ~ 08:30 조식 (카니발 컬쳐 팰리스 지하1층 다과테이블)

(좌장 : 전남대학교 이종숙)

08:30 ~ 09:00 P2Searching for new frontiers in ferroelectric researches

서울대학교 노태원

09:00 ~ 09:20 I7In-situ TEM observation of ferroelectric domain switching

POSTECH 오상호

09:20 ~ 09:40 I8Functionality of domain walls in BiFeO3

건국대학교 이지혜

09:40 ~ 09:55 O4Creep-free ac dynamics in epitaxial ferroelectric BiFeO3 films

서울대학교 신영재

09:55 ~ 10:10 O5Reversible three out-of-plane ferroelectric states in BiFeO3 thin films

KAIST 이진홍

10:10 ~ 10:30 휴식

(좌장 : 인하대학교 정종훈)

10:30 ~ 10:50 I9Strain effect on the visible emission in ferroelectric nanotube: template and wall-thickness effect

숭실대학교 이윤상

10:50 ~ 11:10 I10First-prinsiple study on the piezoelectric properties of hydrofluorinated graphene multilayers

울산대학교 김혜정

11:10 ~ 11:25 O6Freestanding ZnO nanorod/graphene/ZnO nanorod epitaxial double heterostructure for improving piezoelectric nanogenerator

부산대학교 신동명

11:25 ~ 11:40 O7Applications of transmission line impedance models in materials research focusing in energy devices

전남대학교 신의철

11:40 ~ 11:55 O8Low operation voltage of ferroelectric polymer devices induced by X-ray irradiation-mediated atructural transition

GIST 이현준

11:55 ~ 12:10 O9Why no ferroelectricity in polar piezoelectric GaFeO3?

POSTECH 송승우

2월 1일 (일요일)2월 2일 (월요일)


- 9 -

12:10 ~ 16:30 자유시간

16:30 ~ 18:00 Poster Sesstion (P-001 ~ P-114), 학생 포스터 발표 심사진행

18:00 ~ 20:30 Banquet (장소: 카니발 컬쳐 팰리스 지하 1층 심포니 홀)

(사회: 부산대학교 황윤회)

08:30 ~ 09:00 조식

09:00 ~ 12:00 강유전체 연구회 회의

12:00 폐회

2월 1일 (일요일)2월 3일 (화요일)


- 10 -

Poster Session

2015년 2월 2일(월) 16:30 ~ 18:00 (P-001 ~ P-114)

무주리조트 카니발 컬쳐 팰리스 지하1층 로비

P-001

Dependence of electrical properties of Sol–gel derived PZT thick films on crystalline

orientation

V. Annapu Reddy*, Jong-Jin Choi, Jungho Ryu

(재료연구소)

P-002

Enhanced magnetoelectric coupling in a PZT/Metglas bilayer thick film composite

Haribabu Palneedi1,2, Deepam Maurya3, Shashank Priya3, Suk-Joong L. Kang1*,

Si-Young Choi2, and Jungho Ryu2

(1.KAIST, 2.재료연구소, 3.버지니아 공과대학)

P-003

Enhanced polarization of hard polar phases in a heterphase polycrystalline

G. Y. Kim1, S. D. Kim1, Y. M. Rhyim1, S. Y. Yoon2 and S. Y. Choi1*

(1.재료연구소, 2.부산대)

P-004

Temperature Dependance of Magnetic Domains in Co2Z-type Hexaferrite: TEM Studies by

In-situ Heating and Lorentz Microscopy Methods

Sung-Dae Kim1*, Tae-Won Lim1,2, Gi-Yeop Kim1,3, Kee Hoon Kim4 and Si-Young Choi1

(1.재료연구소, 2.경남대, 3.부산대, 4.서울대)

P-005

Electric and structural properties in polar/non-polar multilayers.

Kil-Dong Sung1*, Gi-Yeop Kim1,2, and Si-Young Choi1

(1.재료연구소, 2.부산대)

P-006

Cationic ordeirng and magnetic properties of Re-based double perovskite oxides

T. W. Lim1,2, S. D. Kim1, K. D. Sung1, H. J. Jean3, J. D. Yun2, M. S. Choi1

and S. Y. Choi1*

(1.재료연구소, 2.경남대, 3.부산대)

P-007

Growth and Characterization of LaAlO3 Thin Films Grown by off-axis RF Sputtering

D. H. Kim, C. W W. Bark*

(가천대)

P-008

Synthesis and characterization of UV treated bismuth titnate doped TiO2

M. G. Song, and C W bark*

(가천대)

P-009

Effect of Yb doping on the multiferroic properties of epitaxial BiFeO3 thin films

Yoonho Ahn,1 Jeongdae Seo,1 Jong Yeog Son1,* and Joonkyung Jang2,*

(1.경희대, 2.부산대)


- 11 -

P-010

Source Concentration and Temperature dependence of Microstructure and Properties of ZnO

thin films deposited by MOCVD using Ultrasonic Nebulization

C. H. Lee*, M. S Choi

(계명대)

P-011

Effect of Bi(Ni0.5Ti0.5)O3 doping on structural and piezoelectric properties of BiFeO3-BaTiO3

ceramics

I. J. Hwang1, D. Do1*, M. H. Lee2, J. S. Park2, D. J. Kim2, T. K. Song2, M.-H. Kim2,

S. W. Kim2 and W.-J. Kim2

(1.계명대, 2.창원대)

P-012

Growth of graphene using pulsed laser deposition technique with in-situ monitoring by

reflection high energy electron diffraction

J. H. Kwak, H. J. Lee, S. S. Lee, G. Anoop, and Ji Young. Jo*

(GIST)

P-013

Synthesis of catalytic LaMnO3+d nanoparticles by laser ablation in solution

W. S. Kim, G. Anoop, H. J. Lee, S. S. Lee, J. H. Kwak, H. J. Lee, and Ji Young Jo*

(GIST)

P-014

Superlattice of FeSexTe1-x superconductor thin films

S. Seo1, J. H. Kang2, C. B. Eom2, and S. Lee1*

(1.GIST, 2.University of Wisconsin-Madison)

P-015

Band gap tunability of Fe, Co doped Bismuth Lanthanum Titanate thin films deposited by

PLD

H. An1, J. Y. Han2, C. W. Bark2, S. Lee1*

(1.GIST, 2.가천대)

P-016

BaZrO3 incorporated Ba(Fe,Co)2As2 multilayer epitaxial thin films

J. Lee1, J. D. Weiss2, J. Jiang2, E. E. Hellstrom2, and S. Lee1*

(1.GIST, 2.Florida State Universit)

P-017

Thermoelectric properties of organic multilayers

Hye Jeong Lee1, Hyeon Jun Lee1, Yong Jae Kim2, Eun Ji Lee2, Jae Yoo Choi3,

Hee Suk Kim3, and Ji Young Jo1*

(1.GIST, 2.경남대, 3.한국과학기술연구원)

P-018

Ferroelectric Properties of PMT-PT ceramics modified with Bi2O3

G. B. Kim*

(단국대)

P-019

Thermal Annealing Effects of Zn1-xLixO Grwon by So-Gel Method

J. W. Hyun*, G. B. Kim, J. H. Lee

(단국대)


- 12 -

P-020

Admittance Spectroscopy of the PbSc1/2Nb1/2O3 Polycrystalline Relaxor

Y. J. Kim*

(단국대)

P-021

Effect of sintering temperature on electrical properties of Lead-free (K0.5Na0.5)0.75Ag0.25NbO3

ceramics

J. D. Byun, Y. J. Kim and J. W. Hyun*

(단국대)

P-022

Highly Durable Ti-mesh Based Triboelectric Nanogenerator for Self-Powered Device

Application

Ermias Libnedengel Tsege1, Dong-Myeong Shin1, Seunghun Lee2, Hyung-Kook Kim1,*

and Yoon Hwae Hwang1,*

(1.부산대, 2.고려대)

P-023

Thermal Conductivity and Interfacial Thermal Resistance of Gd2Zr2O7 Thin Films

J. H. Kwak , J. G. Kang, and H. S. Yang*

(부산대)

P-024

Graphene oxide-stimulated myogenic differentiation of C2C12 skeletal myoblasts

J. H. Lee, M. J. Kim, Y. C. Shin, S. E. Kim, J. S. Kim, J. H. Park and D. -W. Han*

(부산대)

P-025

Structures and optical studies of the rare-earth-doped Ca5(PO4)3Cl powders

김영경1, 양호순1, 홍경수2

(1.부산대, 2.한국기초과학지원연구원)

P-026

Structural phase transition and polarization analysis of non-centrosymmetry phases in BiOIO3

Nayoung Song and Bog G. Kim*

(부산대)

P-027

First Principles Study on the Structural Stability between TiO2 Rutile and TiO2 Anatase

K. S. Choi* and C. H. Park

(부산대)

P-028

Microwave Tunable Properties of CPW Phase Shifter Based on Barium Stannate Titanate

Thin Films

H. C. Ryu1* and S. J. Lee2

(1.삼육대, 2.한국전자통신연구원)

P-029

One-dimensional hematite nanostructures for photoelectrochemical water splitting

Do Hong Kim1,2, Young-Seok Shim1, Moon Cheon Woo1, Koo Tak Hong1,

Jong-Myeong Jeon1, Yeon Hoo Kim1, Ki Chang Kwon1, Jun Min Suh1,

Dinsefa Mensur1, Jong-Heun Lee2, and Ho Won Jang1*

(1.서울대, 2.고려대)


- 13 -

P-030

A New Approach to the Negative Capacitance of Ferroelectric Thin Films

Y. J. Kim1*, Y. H. Park1, Y. H. Lee1, H. J. Kim1, W. Jeon1, T. Moon1, K. D. Kim1,

D. S. Jeong2, H. Yamada3, and C. S. Hwang1

(1.서울대, 2.한국과학기술연구원, 3.JST-PRESTO;AIST)

P-031

Study on the wake-up phenomenon of ferroelectric Hf0.5Zr0.5O2 thin films by polarization

switching and discharge behavior

H. J. Kim*, M. H. Park, Y. J. Kim, T. Moon, K. D. Kim, Y. H. Lee, and C. S. Hwang

(서울대)

P-032

Photoactivity of Nanocrystalline Bismuth Vanadate Photoanodes Prepared by Anodic

Electrodeposition

Migyoung Lee*, Hoon Kee Park, Seonyong Lee, Seokhoon Choi, Jaeho Choi,

Byung Suh Han, Boreum Lee, Seo Yun Park, H. W. Jang

(서울대)

P-033

Switchable all oxide capacitor with nm-thick ferroelectric BaTiO3: a direct evidence for

ferroelectric critical thickness

P. Murugavel1,3*, S. R. Lee1,2⧧, Y. J. Shin1,2, Daniel Sando1,2, J.-G. Yoon4

and T. W. Noh1,2

(1.기초과학연구원, 2.서울대 3.Indian Institute of Technology Madras 4.수원대)

P-034

X-ray radiation effects in P(VDF-TrFE) using atomic force microscopy

Owoong Kwon1, Hyeon Jun Lee2, Hosung Seo1, Hye Jeong Lee2, Ji Young Jo2,

Yunseok Kim1*

(1.성균관대, 2.GIST)

P-035

Reaction Pathway of Steam Methane Reforming on Ni3M (111) (M = Rh, Ru) Surface: A

DFT Study

Hanmi Kim, Jaichan Lee*

(성균관대)

P-036

Frequency dependent electromechanical response for distinguishing different origins in

strain-based atomic force microscopy

Daehee Seol, Seongjae Park and Yunseok Kim*

(성균관대)

P-037

Homoepitaxial single- and poly-crystalline SrTiO3 thin films

Sungmin Woo1, Hoidong Jeong1, Sang A Lee1, Hosung Seo1, Morgane Lacotte2,

Adrian David2, Hyun You Kim3, Wilfrid Prellier2, Yunseok Kim1, WooSeokChoi1*

(1.성균관대, 2.Normandie Universite, 3.충남대)

P-038

Crystal and electronic structure of homoepitaxial SrTiO3 thin films with elemental vacancies

Sang A Lee, Hoidong Jeong, Sung Min Woo, Jae-Yeol Hwang, Seul Ki Roh,

Jung Seek Hwang, Sung Wng Kim, and Woo Seok Choi*

(성균관대)

P-039Enhanced Photon Absorption of Titanate Nanosheets

Bongwook Chung1, Minoru Osada2 and Jaichan Lee1*

(1.성균관대, 2.NIMS;MANA)


- 14 -

P-040

Tailoring of Electron-Phonon Coupling in Artificially Designed Superlattice

Minsu Choi, Taejun Hwang, Jiwon Seo, Tran Min Dao and Jaichan Lee*

(성균관대)

P-041

Surface sulfurization of laser-ablated WO3 films for solar water splitting

Chulmin Youn, Joonbong Lee, Heejin Lee, Ho Jin Lee and Taekjib Choi*

(세종대)

P-042

Enhanced Photoelectrochemical Properties of Oxide Semiconductor Heterostructures

Wooyoung Choi, Chulmin Youn, Joonbong Lee, Heejin Lee, Ho Jin Lee, and Taekjib Choi*

(세종대)

P-043

Non-volatile resistive switching effect of LaAlO3/SrTiO3 heterostructures

Sungmoon Hwang1, Yeonsoo Kim2, Baeho Park2 Taekjib Choi1*

(1.세종대, 2.건국대)

P-044

Resistive switching in TiO-SiO composite films after soft breakdown

Tae-Sup Yoo, Chan-Goo Park, and Jong-Gul Yoon*

(수원대)

P-045

Pt-nanoparticle imbedded ZnO-based thin films for ultra-violet photodetector

Khalkhulin Daniil, Seong-Hoon Kim, Hyuna Im, and Jong-Gul Yoon*

(수원대)

P-046

Piezoelectric Properties of Bismuth Copper-based Lead-free Ceramics

Achiri Tange, Hee Sung Kim, Chang Won Ahn and Ill Won Kim*

(울산대)

P-047

Electric Field-Induced Strain of Lead-Free Bi0.5Na0.5TiO3-Bi0.5K0.5TiO3 Ceramics Modified

with BaZrO3

T. H. Dinh, J. K. Kang, C. H. Lee, C. D. Park, Y. H. Hong and J. S. Lee*

(울산대)

P-048

Polar discontinuities and piezoelectric properties of honeycomb lattices

Mohammad Noor-A-Alam and Young-Han Shin*

(울산대)

P-049

Precise measurement of piezoelectric coefficients of PVDF-TrFE films using a Laser

Doppler Vibrometer

Bong Chan Park#, Amir Ullah, Chang Won Ahn and Ill Won Kim*

(울산대)


- 15 -

P-050

CH3NH3PbI3-xClx 두께 변화에 따른 페로브스카이트 태양전지 효율

Sujung Park, and Shinuk Cho*

(울산대)

P-051

Self-polarization in the a lead-free (K0.5Na0.5)(Mn0.005Nb0.995)O3 ferroelectric thin films on

Nb:SrTiO3 substrate from interfacial strain relaxation

Hae Jin Seog1, Chang Won Ahn1, Song A Chae1, Kwang-Eun Kim2, Chan-Ho Yang2,

Tae Yeong Koo3 and Ill Won Kim1*

(1.울산대, 2.KAIST, 3.포항가속기연구소)

P-052

First-principles study of the effect of oxygen vacancies around the 180° ferroelectric

domain walls of tetragonal PbTiO3

Hoe-Cheol Song, and Young-Han Shin*

(울산대)

P-053

Piezoelectric P(VDF-TrFE) Thin Film Power Generators on Paper Substrates for Wearable

Device Applications

Sung Sik Won1,2, Nicholas Mostovych2, Angus I. Kingon2, Ill Won Kim1*

and Seung-Hyun Kim2#

(1.울산대, 2.Brown University)

P-054

Low Temperature Sintering of 0.74(Bi0.5Na0.5TiO3)-0.26SrTiO3 Ceramics by Adding CuO as

a Sintering Aid

D. H. Lee, J. K. Kang, T. H. Hinh and J. S. Lee*

(울산대)

P-055

Properties of [0.98{Bi1/2(Na0.78K0.22)1/2TiO3}-0.02LaFeO3]-Bi1/2(Na0.82K0.18)1/2TiO3 Lead-Free

Piezoceramic Composites

C. H. Hong1*, H. S. Han2, J. S. Lee3, W. Jo1

(1.UNIST, 2.Technische Universität Darmstadt, 3.울산대)

P-056

Investigation of the local work function distribution and resistance change of VO2/Al2O3 and

VO2/TiO2 thin films spanning the metal-insulator transition

Ahrum Sohn1, Teruo Kanki2, Hyun-Tak Kim3,4, and Dong-Wook Kim1,*

(1.이화여대, 2.Osaka University, 3.한국전자통신연구원, 4.UST)

P-057

Structural and electrical properties of epitaxial PbTiO3 thin films on conducting LaNiO3

grown by laser ablation

H. J. Jin, S. H. Oh, and W. Jo*

(이화여대)

P-058

Dielectric properties of PIN-PMN-PT Films Prepared by Aerosol-Deposition Method

S. B. Kang1, Y. M. Kong2, J. H. Ryu3, L. Wang4 and D. Y. Jeong1*

(1.인하대, 2.울산대, 3.재료연구소, 4.Xi’an Jiaotong University)

P-059

A 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 based pyroelectric generator and temperature sensor

Young Joon Ko, Byung Kil Yun, and Jong Hoon Jung

(인하대)


- 16 -

P-060

Room-temperature hydrogen gas sensing properties of Co3O4/Nb2O5 composite nanoparticles

S. H. Kim, S. H. Park, H. J. Kheel and C. M. Lee*

(인하대)

P-061

Fabrication, structure and gas sensing properties of Pt- functionalized ZnS nanowires

S. Park, S. Kim, G. Sun and C. Lee*

(인하대)

P-062

Electric polarization and diode-like conduction in hydrothermally grown BiFeO3 thin films

T. K. Lee and J. H. Jung

(인하대)

P-063

Electrical Properties of Polyvinyldene-fluoride-ZnO Modified CNT Nanocomposite Film by

Spray coating

J. H. Lim1, J. k. Lee1, H. J. Kim1, I. J. No1, Y. M. Kong2, and D. Y. Jeong1*

(1.인하대, 2.울산대)

P-064

Synthesis of Homogeneous Nanocrystalline LiFePO4 by Two Step Polyol Process and Their

Performance

S. J. Kim, J. J. Song, J. H. Gim, B. J. Paul, J. G. Jo, W. G. Park, Y. P. Oh, S. K. Nam,

and J. K. Kim*

(전남대)

P-065

Nanostructure carbon coated LiFePO4 by a scalable polyol combustion synthetic strategy

J. H. Gim1, V. Mathew1, S. H. Kim1, D. Y. Kim1, Y. E. Kim1, D. C. Ahn2, W. B. Im1,

Y. K. Paik3 and J. Kim1,*

(1.전남대, 2.포항가속기연구소, 3.한국기초과학지원연구원)

P-066

Impedance Spectroscopy on Multiferroic Bi0.5K0.5TiO3-BiFeO3

Su-Hyun Moon, Ji-Hoon Kim, Eui-Chol Shin, John Gerard Fisher and Jong-Sook Lee*

(전남대)

P-067

Understanding electrochemical reaction of orthorhombic NCO using in-situ X-ray Diffraction

for sodium ion batteries

J. J. Song, J. H. Gim, S. J. Kim, J. G. Jo, S. H. Park, P. T. Duong, J. H. Yang, J. Lee,

and J. K. Kim,*

(전남대)

P-068

In-depth Electrical characterization of Dye-Sensitized Solar Cells by Impedance Spectroscopy

Method

Dang-Thanh Nguyen, Seok Jae Kim, Eui-Chol Shin, Soon-Hyung Kang, Eun-Mi Han

and Jong-Sook Lee*

(전남대)

P-069

Moving boundary diffusion mechanism in non-monotonic hydration/dehydration AC

relaxation in protonic conducting perovskites

Dong-Chun Cho, Gye-Rok Kim, Eui-Chol Shin and Jong-Sook Lee*

(전남대)


- 17 -

P-070

Polyol-mediated solvothermal synthesis and improved electrochemical performance of novel

K-doped Co3O4 as negative electrode for secondary lithium-ion batteries

J. G. Jo, Z. Xiu, M. H. Alfaruqi, V. T. Trang, S. G. Lee, and J. K. Kim*

(전남대)

P-071

졸-겔 방법 및 다공성 알루미나 멤브레인을 이용하여 제작된 Pb(Zr0.52Ti0.48)O3나노튜브

어레이의 압전 특성 연구

김병훈, 양선아, 강신욱, 부상돈*

(전북대)

P-072

CaBi4Ti4O15세라믹스의 전기적 특성에 감마선 조사가 미치는 영향

전도현, 최기쁨, 조삼연, 부상돈*

(전북대)

P-073

Carbon-nanotube-encapsuled Ferroelectrics Nanocrystals for Energy Harvesting by Mechanical

Movements

J. K. Han1, D. H. Jeon1, S. Y. Cho1, S. W. Kang1, S. A Yang1, K. Y. Choi2, E. J. Ra3,

J. S. Lim3, and S. D. Bu1*

(1.전북대, 2.서울대, 3.한국화학연구원)

P-074

The use of (NH4)2WS4 precursor as hole extraction layer in organic photovoltaic cells

Quyet Van Le, Thang Phan Nguyen, Soo Young Kim*

(중앙대)

P-075

Facile route for the synthesis of MoS2 and WS2 nano dots

Thang Phan Nguyen, Kyoung Soon Choi, and Soo Young Kim*

(중앙대)

P-076

Piezoelectric and Electrical Properties of Li-doped (Bi0.5Na0.5)TiO3-PVDF Composite for

Energy Harvesting

Joong-Hyeon Ahn and Jung-Hyuk Koh*

(중앙대)

P-077

Enhanced Piezoelectric and Dielectric Properties of Na0.5K0.5NbO3-CaCu3Ti4O12 Lead-Free

Composite

Jae-Hoon Ji and Jung-Hyuk Koh*

(중앙대)

P-078

Temperature Dependent Ferroelectric and Field-Induced Strain Response of Nb-doped

BNBT-SZ Lead-free Piezoelectric Ceramics

Adnan Maqbool, Ali Hussain, Jamil Ur Rahman, Rizwan Ahmed Malik, Tae Kwon Song,

Won-Jeong Kim, and Myong-Ho Kim*

(창원대)

P-079

Compositional-induced structural and non-ergodic to ergodic relaxor transition in lead-free

Ta-doped Bi0.5(Na0.84K0.16)0.5TiO3–SrTiO3 ceramics

Rizwan Ahmed Malik1, Ali Hussain1, Arif Zaman2, Tae Kwon Song1, Won-Jeong Kim1

and Myong-Ho Kim1,*

(1.창원대, 2.Abdul Wali Khan University)


- 18 -

P-080

새로운 비납계 BiFeO3-BaTiO3 압전 재료의 물성 평가

D. J. Kim1, M. H. Lee1, J. S. Park1, M.-H. Kim1, S. S. Kim1, D. Do2, H. Y. Lee3,

and T. K. Song1*

(1.창원대, 2.계명대, 3.Ceracomp Co., Ltd)

P-081

Structural, electrical and multiferroic properties of chemical solution deposited Aurivillius

Bi7Fe3Ti3-xNbxO21 thin films

C. M. Raghavan, J. W. Kim, J. Y. Choi, M. J. Lee and S. S. Kim*

(창원대)

P-082

Study on the new type of piezoelectric actuator utilizing smooth impact drive mechanism

M. H. Park1, H. H. Jeong2, S. S. Jeong3 and T. G. Park3*

(1.국방기술품질원, 2.SAMJEON CO., LTD, 3.창원대)

P-083

Ferroelectric properties of (1-x)BiFeO3-xBaTiO3 solid-solution thin films

J. S. Park, M. H. Lee, S. W. Kim, D. J. Kim, S. J. Han, S. Kumar, M-H. Kim, W-J. Kim,

and T. K. Song*

(창원대)

P-084

Na0.5Bi0.5TiO3-BaZrO3 textured ceramics prepared by reactive templated grain growth method

Ali Hussain, Jamil Ur Rahman, Adnan Maqbool, Rizwan Ahmed Malik, Tae-Kwon Song,

Won-Jeong Kim, and Myong-Ho Kim*

(창원대)

P-085

New high Curie temperature lead-free piezoceramics in BiFeO3-BaTiO3 solid solution

이명환1, 김다정1, 박진수1, 김명호1, 송태권1† , 김상욱1, 김원정1, 김상수1, 장기완1, 도달현2,

정일경3

(1.창원대, 2.계명대, 3.부산대 유전체물성연구소)

P-086

Study on the output characteristics of the lambda type ultrasonic motor depending on the

polarization direction of the piezoelectric ceramic

S. K. Cheon1, S. S. Jeong1, Y. W. Ha1, B. H. Lee1, H. I. Jun2, T. G. Park1*

(1.창원대, 2.Mattron corp)

P-087

Structure and electrical properties of rare-earth substituted K0.5Bi4.5Ti4O15 thin films prepared

by chemical solution deposition

J. Y. Choi, J. W. Kim, C. M. Raghavan, M. J. Lee and S. S. Kim*

(창원대)

P-088

Optical ad electrical properties of band-gap controlled Ge doped ZnO1-xSx thin films

S. J. Han1, S. W. Kim1, M. H. Lee1, J. S. Park1, D. J. Kim1, D. Do2, M. H. Kim1,

T. K. Song1, and W. J. Kim1*

(1창원대, 2계명대)

P-089

Metal-insulator transition in NdNiO3 by hydrogen doping

C. D Oh*, S. Y. Heo, H. M. Jang and J. W Son

(POSTECH)


- 19 -

P-090

Hydrogen-bonding effects in organohalide-perovskite-based solar cells: first-principles study

June Ho Lee* and Hyun Myung Jang

(POSTECH)

P-091

Modulated Spin Structure responsible for the Magnetic-Field-Induced Polarization Switching

in Multiferroic TbMn2O5

Jung-Hoon Lee, Seungwoo Song and Hyun Myung Jang*

(POSTECH)

P-092

Rapid Thermal Heating Effects on the Zn0.85Mg0.15O:Ga Thin Films

Byeong-Eog Jun*, Sunwoo Kim, Sangwoo Kim, Seongmin Lee, Jimin Koo,

and Jong Rim Lee

(KAIST)

P-093

Preparations of the Ba1-xEuxTiO3 Ceramics in the Nitrogen Gas Ambient

Byeong-Eog Jun*, Minki Kim, Seung-Min Oh and Jong Rim Lee

(KAIST)

P-094

Optical Characterization of Semiconductor ZnxCu1-xO Nanoparticles Prepared by

Hydrothermal method

J. P. Kim*, S. H. Jung, J. H. Kim, M. G. Ha, J. S. Bae, T. E. Hong, E. D. Jeong,

K. S. Hong, J. S. Jin

(한국기초과학지원연구원)

P-095

Direct Adhesion of Polyphenylenesulfide Resin and Polymeric Film on Copper by Surface

Modification

Eun Hyuk Chung1, F. Nawaz Khan1,2, Tae Eun Hong1, Jong Pil Kim1, Jong-Seong Bae1,

and Euh Duck Jeong1*

(1.한국기초과학지원연구원, 2.VIT University)

P-096

Glass formation conditions and photophysical properties of the samarium-containing binary

and ternary tellurium glass ceramics

강보배1, 하명규1, 김현규1, 양호순2, 홍경수1

(1.한국기초과학지원연구원, 2.부산대)

P-097

BaTiO3 나노 입자의 소성 시 첨가제에 따른 미세구조 및 유전특성

The microstructure and the dielectric properties with additives in the sintering of BaTiO3

nano particle

Jae Won Kang1,2, Hyo Soon Shin1*, Dong Hun Yeo1, Dae Yong Jeong2

(1.한국세라믹기술원, 2.인하대)

P-098

4상 혼합 유전체 기판 소재의 상 분율에 따른 미세구조와 기계적 강도

Chang Hyun Lee1,2, Hyo Soon Shin1*, Dong Hun Yeo1, Hyo Tae Kim1, Sahn Nahm2

(1.한국세라믹기술원, 2.고려대학교)

P-099

ZnO-B2O3계 glass 첨가에 따른 Ca[Li1/3Nb2/3)0.8Ti0.2]O3-δ 세라믹스의 마이크로파 유전특성

Chi-Seung In1,2, Dong-Hun Yeo1*, Hyo-Soon Shin1, Sahn Nahm2

(1.한국세라믹기술원, 2.고려대)


- 20 -

P-100

Influence of some metal electrodes on dielectric properties of PTC ceramic thermistor

Myoung Pyo Chun*

(한국세라믹기술원)

P-101

High Performance Lead Free Piezoelectric Ceramic Composite

S. M. Jang* and S. J. Jeong

(한국전기연구원)

P-102

The study of thermoelectric properties in cobalt silicide/silicon thin film thermoelectric

devices

Soojung Kim1,2, Hyundal Jung1, Wonchul Choi1,3, Junsoo Kim1, Dongsuk Jun1,

Taehyoung Zyung1,2 Taekwang Kim1, Eun-su Nam1 and Seungen Moon11,*

(1.한국전자통신연구원, 2.UST, 3.KAIST)

P-103

Thermoelectric properties of sputtered silicon membrane in vertical direction

Junsoo Kim1, Wonchul Choi1,3, Soojung Kim1,2, Taekwang Kim1, Hyundal Jung1,

Dongsuk Jun1, Taehyoung Zyung1,2, Seung-Min Lee4, Eun-su Nam1 and Seungen Moon1,*

(1.한국전자통신연구원, 2.UST, 3.KAIST, 4.Hanbeam co,)

P-104

Low Power Consumption and High Sensitive Micro Alcohol Gas Sensor based on

Co-planar Micro-heater and Screen Printing Technique

S. E. Moon1*, T. K. Kim1, J. S. Kim1, W. C. Choi1, B. H. Park2, J. C. Kim2, J. J. Jung3

and D. J. Yoo3

(1.한국전자통신연구원, 2.건국대, 3.Sentech Korea)

P-105

Fabrication and Field Effect Electronic Properties of Amorphous ZnO-SnO2 Superlattice Thin

Films

Su-Jae Lee, Chi-Sun Hwang, Jae-Eun Pi, and Kyoung-Ik Cho

(한국전자통신연구원)

P-106

ALD 방법으로 증착된 Al2O3 박막의 열전도도 측정

Wonchul Choi1,3, Soojung Kim1,2, Hyundal Jung1, Junsoo Kim1, Dongsuk Jun1,

Taehyoung Zyung1,2, Eunsoo Nam1, Seungmin Lee4, and Seungen Moon1,*

(1.한국전자통신연구원, 2.UST, 3.KAIST, 4.Hanbeam co,)

P-107

고압 브릴루앙 산란을 이용한 Polydimethylsiloxane의 고압특성 분석

신선협1, 고재현1*, 고영호2, 김광주2

(1.한림대, 2.국방과학연구소)

P-108

Phase Transition Behaviors of Lead-Free (NaBi)TiO-BaTiO Single Crystals Studied

by Inelastic Light Scattering Spectroscopy

Byoung Wan Lee1, Jun Ho Ryeom1, Jae-Hyeon Ko1, Xiaobing Li2 and Haosu Luo2

(1.한림대, 2.Shanghai Institute of Ceramics)

P-109

Phase transition behaviors of PbZr0.8Ti0.2O3 single crystals as revealed by elastic anomalies

and central peaks

Min-Seok Jeong1, Jae-Hyeon Ko1*, Seiji Kojima2, Alexei A. Bokov3, Xifa Long3,

and Zuo-Guang Ye3

(1.한림대, 2.Univ. of Tsukuba, 3.Simon Fraser Univ.)


- 21 -

P-110

Instability of Reset Parameters Due to Intrinsic Property of Conducting Filaments Formed at

Low Compliance Current in Unipolar Resistance Switching

Sang-Chul Na1, Keundong Lee2, Min Chul Chun1, Young-Sun Kwon1, Hye-Jin Shin1,

Ji Seok Im1, Sangik Lee2, Bae Ho Park2 and Bo Soo Kang1*

(1.한양대, 2.건국대)

P-111

The Effects of Etch Stopper Layer on Electrical Properties of Tin monoxide Thin Film

Transistors Prepared by RF Magnetron Sputtering

J.-Y. Kim, J.-M. Song, K. M. Yu, B. S. Bae, and E.-J. Yun*

(호서대)

P-112

A Study on the High Temperature-dependence of Electrical Properties in Solution-deposited

Zinc Tin Oxide Thin Film Transistor Operated in the Saturation Region

K. M. Yu, B. S. Bae, and E.-J. Yun*

(호서대)

P-113

High Temperature Dielectric Relaxations in BiFeO3-(Bi,K)TiO3 Ceramics

Jung Hwan Kim1, Jeong Seog Kim1, Wook Jo2, Chae Il Cheon1*

(1.호서대, 2.UNIST)

P-114

First-principles Investigation of Bistability in Ga- and In-doped CdF2

M. S. Kim* and C. H. Park

(부산대)

ABSTRACTS

Oral Session

제 24회 유전체물성 심포지엄 및 제 16회 강유전체 소자/소재 워크숍2015. 2. 1~3, 무주리조트 카니발 컬쳐 팰리스

P1

16:10 ~ 16:40, February 1

Revisit of Lead-free Piezoelectric Material Systems

for Practical Device Applications

Seung-Hyun Kim1*, Sung Sik Won2, Vineeth Venugopal1, Chang Won Ahn2,

Ill Won Kim2, and Angus I. Kingon1

1School of Engineering, Brown University, Providenece, RI02912, USA2Dept. of Physics and Energy Harvest-Storage Center, Univ. of Ulsan, Korea

Legislation is already in place in USA and Europe to ban the use of Pb in industrial products,

including piezoelectric actuators, with exemptions currently being maintained for the ubiquitous lead

zirconate titanate (PZT) class of materials until viable lead-free alternatives are developed. While it

is indeed a formidable materials science and engineering task to create a material to replace the

versatile and well studied PZT system, over the past number of years R&D into lead-free

piezoelectric materials has progressed steadily, leading to the expectation that the commercial

introduction of lead-free piezoelectric devices may occur in the near future, possibly prior to the

expiration of the current EU exemption in 2016. Many companies that currently utilize PZT

transducers and sensors have developed strong knowledge and capabilities in the area of lead-free

materials.

Our research direction is ambitiously designed to make up the knowledge gap and to leapfrog

our academic society into a position in which it can launch practical lead-free piezoelectric

devices, with this position including protectable intellectual property. In developing a strategy we

intensively performed systematic experiments and compared the results with all reported R&D on

lead-free piezoelectric materials (research literature and IP). Based on above data we also had some

careful and selected discussions with other leading groups including representative industry in

lead-free piezoelectric materials for practical applications.

The key strategic research involving the choice of materials, process method, integration into

device assembly and operation parameters of the devices will be discussed here in detail.

*E-mail : [email protected]

Contact Phone : 010-9262-9392


P2

08:30 ~ 09:00, February 2

Searching for new frontiers in ferroelectric researches

Tae Won Noh

Dept. of Physics and Astronomy, Seoul National Univ. & Center for Correlated Electron

Systems, Institute of Basic Science

Ferroelectricity, defined by the existence of a switchable spontaneous polarization, has attracted

significant interest since its discovery in 1920. Many decades of extensive research has enabled a

deep understanding of ferroelectric phenomena. More recently, with the rapid advances in thin film

fabrication techniques for oxide materials, new fascinating scientific phenomena, particular to thin

film ferroelectric materials, have been uncovered. As one of new initiatives of IBS, we are

currently searching for new frontiers in ferroelectric researches. Especially, we are investigating a

couple of intriguing effects, including flexoelectricity and ferroelectric tunnel junctions (FTJ).

The flexoelectric effect is the electro-mechanical coupling that generates an electric field by a

strain gradient. Although this phenomenon exists in all dielectric materials, there have been few

studies devoted to it due to the small size of the effects in bulk and difficulties in systematic

control of strain gradient. Our recent studies, however, have shown that strain gradients in epitaxial

thin films can be 6-7 orders of magnitude larger than in their bulk counterparts [1]. Here, I will

review the recent progress regarding the flexoelectric effects in epitaxial ferroelectric thin films,

suggesting that we can make use of flexoelectric effects by carefully controlling the strain gradient.

Investigation of the ferroelectricity at the nanoscale enables us to understand the fundamental

properties of this phenomenon. For instance, the critical thickness for existence of ferroelectricity

and its connection with the effect of the depolarizing field, is a long-standing issue that has

received much research attention. This issue is particularly relevant in the context of the recent

advent of memory devices based on ultrathin layers: so-called FTJ. Recently, we have successfully

fabricated ferroelectric BaTiO3 films just a few unit cells in thickness, on SrRuO3-coated SrTiO3

substrates. Our studies on all-oxide capacitor structures based on these ultrathin films show that the

critical thickness for ferroelectricity is dependent on the top electrode (using SrRuO3, La0.7Sr0.3MnO3,

or without top electrode). This electrode-dependent critical thickness highlights the importance of the

interfacial effect between the ferroelectric material and the electrode for stabilizing ferroelectricity.

References

[1] D. Lee et al., Phys. Rev. Lett. 107, 057602 (2011).


I1

16:40 ~ 17:00, February 1

Frequency and temperature dependence of incipient piezoelectricity

W. Jo1*, C. Groh2 and J. Rödel2

1School of Materials Science and Engineering, Ulsan National Institute of Science and

Technology, Ulsan 689-798, Korea2Institute of Materials Science, Technische Universität Darmstadt, Alarich-Weiss-Straße 2,

64287 Darmstadt, Germany

In response to the world-wide environmental issues, (Bi1/2Na1/2)TiO3(BNT)-based

piezoceramics have been extensively studied over the last two decades. Though the overall

piezoelectric performance of the BNT-based piezoceramics has turned out to be too low to compete

the market dominating PZT-based piezoceramics, the strain properties, i.e., actuating performance,

have been shown to exceed any known piezoceramics, when the composition of materials are

appropriately tuned. A number of compositional studies have shown that the appearance of this

large strain is not confined to certain material classes but a rather universal phenomen on when the

A-site of perovskite structure is co-occupied with heterovalentions. In addition, the observed large

strains are featured by are latively large hysteresis and poor small signal piezoelectric properties. To

unveil the underlying mechanism for the unconventionally large strains, we have performed a

systematic investigation of the effect of measurement frequency and temperature on the strain

behavior. In comparison to the conventional piezoceramics such as PZT, it was observed that this

large strains are more susceptible both to the measurement frequency and to measurement

temperature. In this contribution, we would like to present the detailed experimental results for

proposing a new concept, incipient piezoelectricity, as an origin for the unconventionally large strain

behaviors in BNT-based piezoceramics.


Contact Phone : 052-217-2347 (010-6224-3879)


I2

17:00 ~ 17:20, February 1

Lead-free piezoelectric BiFeO3-BaTiO3 thick films

Da Jeong Kim, Myang Hwan Lee, Jin Su Park, Tae Kwon Song*

School of Materials Science and Eng., Changwon Nat’l Univ., Gyeongnam 641-773,

Korea

Because piezoelectric multilayer actuator devices are fabricated by thick film processes such as

tape-casting process, it is very important to develop thick films in the new lead-free piezoelectric

system. BiFeO3-BaTiO3 (BF-BT) based system is one of new high Curie temperature and good

piezo-response materials, which have been challenging to texture and bulk by thick film process.

We investigated 0.67BF-0.33BT (BF-BT33) thick films without any templates for the improvement

of grain orientation. The piezoelectric constants of d33 and d33* the sintered thick film were 189

pC/N and 260 pm/V when it was quenched at temperature of 960 oC. The Curie temperature was

about 470 oC. BF-BT33 thick film has remnant polarization Pr = 20 μC/cm2 and coercive field Ec

= 22 kV/cm. These results are as good as those of bulk ceramics in lead-free BF-BT system.

Though polarization direction of (111) in BF, better piezoelectric property is expected in (100)

direction in BF-BT system. Bi4Ti3O12 templates were also tried for the alignment of grains in

BF-BT33 to improve piezoelectric properties. The preliminary results will be presented.

Fig.1 P-E hysteresis loops (a) and S-E curves (b) of the BF-33BT bulk ceramics made by tape

casting method.




I3

17:20 ~ 17:40, February 1

Practical Applications of Bi0.5(Na,K)0.5TiO3 based Lead-free Piezoelectric

Ceramics

Chang Won Ahn1,*, Gang Ho Choi1, Hee Sung Kim1, Sung Sik Won1, Hae Jin Seog1,

Song A Chae1, Ki Bong Jang2, Yun Po Ok2, Hyon Ho Chong2, and Ill Won Kim1

1Department of Physics and EHSRC, University of Ulsan, Ulsan 680-749, Korea2R&D Center, Samjeon Co. Ltd, Ulsan 689-934, Korea

In the past decade, lead-free piezoelectric ceramics such as (K,Na)NbO3 (KNN) and

Bi0.5Na0.5TiO3 (BNT)-based materials have been widely studied as replacements for lead-based

materials because of environmental concerns about Pb-containing materials such as lead zirconate

titanate (PZT), which contains more than 60 wt.% Pb. Recently, many studies on lead-free

piezoelectric ceramics have been published. Among various lead-free piezoelectric materials,

BNT-based ceramics are of particular interest because of their high electric-field induced strain and

blocking force, which play important roles in piezoelectric actuator applications. Even though many

studies have reported the physical properties of BNT-based lead-free ceramics, only a few reports

are available about their applications such as multilayer ceramics actuators (MLCAs).

In the present study, we developed a piezoelectric MLCA was fabricated using active layers of

BNKT22:CuO 1.0 mol.% and a Ag-Pd (9:1) internal electrode, and then the performance of a

device with this MLCA was investigated. The average sound pressure level of this device was

comparable to that of the lead-based piezoelectric ceramics speaker in the frequency range between

660 and 20,000 Hz. Therefore, BNKT22:CuO 1.0 mol.% piezoelectric MLCA speakers are good

candidates for lead-free audible sound devices




I4

17:40 ~ 18:00, February 1

Piezoelectric Micromachined Ultrasonic Transducer (pMUT) by Granule Spray

in Vacuum Process (GSV)

Jungho Ryu1*, Joontaek Jung2, Hongsoo Choi2, Woon-Ha Yoon1, Dong-Soo Park1,

Jong-Jin Choi1, Cheol-Woo Ahn1, Jong-Woo Kim1, and Hyung-Dong Hahn1

1Korea Institute of Materials Science (KIMS), Changwon 642-8312Daegu Gyeongbuk Institute of Science and Tech.(DGIST) Daegu 711-873

Ultrasonic transducers have been widely used for various applications including medical

imaging, biological therapy, ultrasonic communication, and rangefinder. MEMS based piezoelectric

micromachined ultrasonic transducer (pMUT) is a potential candidate for next generation ultrasonic

transducer since it has significant advantages over traditional ultrasonic transducers. Thin film

fabrication techniques such as sol-gel, sputtering are generally adapted for the fabrication of pMUT

to deposit piezoelectric PZT/AlN thin-film, however, those techniques have limitation of film

thickness which may cause the actuation power and process itself is relatively costly and time

consuming. In order to overcome these shortcomings of typical thin film process for pMUT, we

applied the room temperature granule spray in vacuum process (GSV) to deposit piezoelectric PZT

layer for MEMS pMUT device. PZT thick films were directly patterned by typical PR lithography

and lift off process combined with PZT deposition followed by thermal treatment, top electroding,

DRIE etching process and packaging. The fabricated the pMUT by GSV was characterized by

measuring resonant frequency, electromechanical coupling coefficient, displacement of the membrane

and the ultrasonic intensity. The pMUT by GSV is expected to present enhanced ultrasound

intensity compared with the sol-gel based pMUT as well as reducing the fabrication time and cost.




I5

19:00 ~ 19:20, February 1

Understanding Defects in Ferroelectrics and Their Application

Soonil Lee

Energy & Environmental Division, Energy Conversion Materials Team, Korea Institute of

Ceramic Engineering and Technology, Geumcheon-gu, Seoul 153-801, Korea

Ferroelectric ABO3 has been systematically investigated in regard to the solubility region

around stoichiometric ABO3 with a combination of techniques regarding the thermodynamics, defect

chemical reactions, and Landau-Devonshire theory. Self-consistent data was obtained and successfully

modeled analytically with defect reactions across the dependant variables of A/B, temperature, and

oxygen partial pressure. From this study, we can determine the defect chemistry of ABO3, obtain

reliable enthalpies of defect formation for the partial Schottky reactions, and determine the

relationship between ferroelectric properties and defect concentration. Those ferroelectric materials

are mostly requiring insulating ferroelectric materials for better ferroelectric properties. However,

there is lack of studies on the ferroelectrics with high concentration of electronic charge carriers.

This paper demonstrates ferroelectric oxides in the unusual condition where the concentration of

electronic carriers is close to a metal-insulator transition; in certain structures and compositions

these materials have properties of interest for ferroelectric based thermoelectric applications. In the

heavily reduced perovskite, tungsten bronze structured, and perovskite layer structured materials,

themopower and electrical conductivity anomalies are observed depending on the carrier

concentration. With this work, the complex nature of the oxygen defect engineered ferroelectrics is

discussed in terms of the thermoelectric properties and coupling of ferroelectrics and thermoelectrics.

Acknowledgements:

Clive A. Randall, Steve Perini, Gaiying Yang, Rudger H. T. Wilke, Susan Trolier-McKinstry, Shujun

Zhang, Sinan Dursun, Cihangir Duran, Takashi Teranishi, Daniel J. Magagnosc, Jonathan A. Bock, Paul

Moses, Jeff Long, Amanda Baker, Weiguo Qu, Petro Maksymovych, Arthur P. Baddorf

*E-mail : [email protected], [email protected]



I6

19:20 ~ 19:40, February 1

BiVO4 단결정의 Incommensurate Twin Domain Wall에 관한 연구

장 민수1, 조 성호2*

1부산대학교 물리학과 명예교수, 부산 609-735, 2고려대학교 물리학과 명예교수, 서울 136-701,

BiVO4 은 255 에서 (4/m) 를 갖는 로부터 (2/m) 의

로 (2nd order) 하는 물질이다. 이 물질은 에서 인 로서 서냉

(slow cooling)과 Czochralski 으로 을 시킬 수 있다. (ferroelastic

crystal)은 (ferroelastic phase)의 에서 는 같으면서 서로 다른 둘 의

(orientation state; OS)를 갖는다. 이 물질의 저온상인 강탄성상에서 여러 들이

측정한 Incommensurate Twin Domain Wall(W' )이 각각 다른 값으로 보고되어 있다.

이점에 대하여 본 에서는 그 원인을 조사하기 위하여 과 의 를 이

용하여 Sapriel 과 Aizu의 이론으로 W' ()을 계산하였으며, 그 계산 값과 여

러 연구자가 실험으로 측정한 W' (exp)으로부터 의 층밀리기 변형률()을

계산하였다. 계산결과에 의하면 서냉법으로 시킨 의 층밀리기 , 이

Czochralski법으로 시킨 의 값보다 2배 정도 큰 값을 보였다. 그리고 아래 그림과 같

이 격자상수를 사용하여 계산한 W’ 쌍정구역 벽은 와 일 때 축

(;[100])으로부터 양의 기울기를 갖는 W' 쌍정구역 벽은 와 로 각각

계산되었다. 본 연구 로부터 이 되는 에 에 남아있는 변형력과 강

탄성상으로 상전이하면서 격자변형으로 생성된 변형력에 의한 층밀리기 , 이 W' 쌍정

구역 벽의 형성에 영향을 미쳤다고 생각한다.

*: 본 연구는 대한민국학술원 연구비지원에 의해 수행되었습니다. 책임연구자.E-mail : [email protected] and [email protected]

Contact Phone : 장 민수: 010-3339-0124, 조 성호: 010-3297-3470


I7

09:00 ~ 09:20, February 2

In-situ TEM Observation of Ferroelectric Domain Switching

J. K. Lee1, G. Y. Shin1, K. Song1, Ho Nyung Lee2, W. S. Choi2, L.-Q. Chen3

and S. H. Oh1*

1Department of Materials Science and Engineering, POSTECH, Pohang 790-7842Materials Science and Techology Division, Oak Ridge National Laboratory, Oak Ridge,

TN 37831, USA3Department of Materials Science and Engineering, The Pennsylvania State University,

University Park, PA 16802, USA

We report in-situ transmission electron microscopy observations of the 180° polarization

switching process of an epitaxial PbZr0.2Ti0.8O3(PZT) thin film capacitor. The preferential, but

asymmetric, nucleation and forward growth of switched c-domains were observed at the

PZT/electrode interfaces, arising due to the built-in electric field induced at each interface. The

subsequent sideways growth of the switched domains was inhibited by the depolarization field due

to the imperfect charge compensation at the counter-electrode and also at the boundaries with

preexisting a-domains, which contributed further to the asymmetric switching behavior. It was found

that the preexisting a-domains split into fine a- and c-domains constituting a 90° stripe domain

pattern during the 180° polarization switching process, revealing that these domains also actively

participated in the out-of-plane polarization switching. The real-time observations uncovered the

origin of the switching asymmetry and further clarified the importance of charged domain walls and

the interfaces with electrodes in the ferroelectric switching processes.

*E-mail :[email protected]



I8

09:20 ~ 09:40, February 2

Functionality of Domain Walls in BiFeO3

J. H. Lee1,2*, I. Fina2,3, X. Marti3, Y. H. Kim,2,5 D. Hesse2, and M. Alexe2,3

1Department of Quantum Phase and Device, Department of Physics, Konkuk University,

Seoul, Korea2Max Planck Institute of Microstructure Physics, Halle (Saale), Germany

3Department of Physics, University of Warwick, Coventry, United Kingdom4Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles

University, Praha, Czech Republic5Korea Research Institute of Standards and Science, Daejeon, Korea

Ferroelectricity and ferromagnetism had succeeded in the realms of fundamental research, sensing and memory technologies independently before the dawn of multiferroics. The study of domain walls regarded as natural interfaces in these ferroic materials has been brought into attention due to their abnormal properties compared to the host materials. One of these materials, multiferroic BiFeO3 (BFO), which shows high transition temperature of both ferroic order parameters, has been intensively explored because of its unique characteristics of the domain wall, such as increased magnetoresistance, remarkable photovoltaic effect and enhanced conductivity. However, until now there have been only few attempts to control and tune the physical properties of domain walls in a designed way. Among them, tuning the conduction at domain walls is one of the most effective ways with high potential for future applications.

In this presentation, it is proposed to make use of the ferroelectric domain walls in the multiferroic material BFO, which are also conducting and ferromagnetic, and which are intrinsically two dimensional hybrid nano-objects of multiferroic type in a single materials. It is also shown that one can modulate the electronic transport across the ferromagnetic and ferroelectric domain walls in BFO via an external magnetic field, resembling the anisotropic magnetoresistance (AMR) in archetypical metallic ferromagnets. At the same time, BFO preserves two stable and switchable electric polarization states and one can manipulate the ferroelectric domain walls, and thus magnetization, via an electric field.

The electronic transport occurring just through the ferroelectric domain walls is discriminated from the contribution occurring in the bulk, and the conduction mechanism at the domain walls is identified. The extracted contribution of ferroelectric domain walls to the electronic transport occurs to be responsive to an external magnetic field, with a marked unidirectional anisotropy, accompanied by a visible hysteresis, which is ascribed to the coupling of the ferromagnetic domain walls to the bulk antiferromagnetic domains in BFO, similar to that found in ferromagnetic/antiferromagnetic structures. Our results open a perspective for using multiferrocity of domain walls for nanoelectronics.




I9

10:30 ~ 10:50, February 1

Strain effect on the visible emission in ferroelectric nanotubes: template and

wall-thickness effect

Y. S. Lee1*, C. H. Jeon1, J. K. Han2, and S. D. Bu2

1Department of Physics, Soongsil University, Seoul 156-7432Department of Physics, Chonbuk National University, Jeonju 561-756

We investigated the strain effect on temperature-dependent photoluminescence property in the

clamped (with template) and free-standing (without template) PbTiO3 (PTO) nanotubes. The

wall-thickness of nanotubes was varied from 25 to 80 nm with the outer diameter fixed to 420 nm.

While all nanotubes show sizable green/yellow emission, the temperature dependent shift of the

emission energy is significantly suppressed in the clamped PTO nanotubes, which is attributed to

the lattice strain driven by the template clamping. This clamping effect is more significant for

thinner nanotubes. Even in the free-standing PTO nanotubes the temperature-dependence of emission

is affected by the wall-thickness. The similar behavior is identified in the Pb(Zr,Ti)O3 nanotubes.

Our finding is the clear manifestation of the template and geometrical shape effect on the optical

property of the nanotubes.




I10

10:50 ~ 11:10, February 1

First-principle study on the piezoelectric properties of hydrofluorinated graphene

multilayers

Hye-Jung Kim and Young-Han Shin*

Department of Physics and EHSRC, University of Ulsan, Ulsan 680 749

Hydrofluorinated graphene (C2HF)n possesses electric dipole moment and piezoelectric properties

due to the inversion symmetry breaking under the selective adsorption of H and F atoms. Among

the possible conformations (chair, boat, zigzag, and armchair), the chair (C2HF)n is energetically

most stable. Therefore, we just study the piezoelectric properties of AA-stacked chair (C2HF)n

multilayers. The electric polarization of a chair (C2HF)n monolayer is known to be 47.3 pC/m along

the z direction normal to the surface, and its computed piezoelectric constants are e31=13.0 pC/m

and d31=4.71⨯10-14 m/V [1]. In the dipolar chair (C2HF)n multilayers, we examine their

piezoelectricty and uncompensated depolarization field effects as the number of layers increases. In

our calculations, because of the depolarization field generated in the opposite direction of dipole

moment, the electron and hole carriers are generated on top and bottom layers. Through the

calculation of the average layer piezoelectric constant e31/l in l-layered chair (C2HF)n multilayers, we

confirm that the piezoelectricity of the bilayer is about three times larger than that of the

monolayer and bulk (C2HF)n. Moreover, we find that the induced carriers on the top and bottom

layers play a significant role in the piezoelectric enhancement of the bilayer.

[1] H. J. Kim, M. Noor-A-Alam, J. Y. Son, and Y. -H. Shin, Chem. Phys. Lett. 603, 62

(2014).




O1

19:40 ~ 19:55, February 1

Antiferroelectric HfxZr1-xO2 thin films for the energy-related applications

M. H. Park*, H. J. Kim, Y. J. Kim, T. Moon, K. D. Kim, Y. H. Lee, and C. S.

Hwang

Department of Materials Science and Engineering and Inter-university Semiconductor

Research Center, College of Engineering, Seoul National University, Seoul 151-744,

Korea.

In this presentation, antiferroelectric (AFE) HfxZr1-xO2 (HZO, x=0.1-0.4) thin films are reported

as new Si-compatible materials for various energy-related applications including pyroelectric energy

harvesting, electrocaloric cooling, electrostatic energy storage, and infrared sensing. Hf0.2Zr0.8O2 film

could work as a pyroelectric energy harvester using the Olsen cycle with the harvested energy

densities (HEDs) of 11.5 J/cm-1 per cycle, which are ~7.6 times larger than the largest value to

date.[1] The electrocaloric effect (ECE) of HZO films was also firstly examined, and the maximum

ΔT values of the Hf0.2Zr0.8O2 film were 13.4K at 307K.[1] The wide temperature range for the

large ΔT values of the HZO films are expected to be promising for the practical cooling cycle

with large magnitude of the reversible work. Moreover, the large capacitance of the HZO films due

to the field-induced transition between the ferroelectric and AFE phase can be used for electrostatic

energy storage and high-charge capacitors. Hf0.3Zr0.7O2 film showed the large energy storage density

(ESD) up to ~46 J/cm3, and the ESD value did not decrease with increasing temperature up to

448K, which was limit of our measurement system.[2] Furthermore, the k2 and Fv values, which are

the figures of merit for conventional pyroelectric energy conversion and infrared detection for

thermal imaging, of the Hf0.2Zr0.8O2 film were 24.4x10-3 and 32.0x10-2 m2/C, respectively, which

prove that Hf0.2Zr0.8O2 is also a promising material for these applications. From these results, thin

HZO films are believed to be a promising candidate for the various energy-related applications.

[1] M. H. Park, H. J. Kim, Y. J. Kim, T. Moon, K. D. Kim, and C. S. Hwang, Nano

Energy, accepted (2014).

[2] M. H. Park, H. J. Kim, Y. J. Kim, T. Moon, K. D. Kim, and C. S. Hwang, Adv. Energy

Mater. 4, 1400610 (2014).




O2

19:55 ~ 20:10, February 1

Structural properties of strained epitaxial PbVO3 (001) thin films

Seol Hee Oh1, Hye-Jin Jin1, Hae-Young Shin1, Seokhyun Yoon1, Jai Seok Ahn2,

Janghwan Cha3, Suklyun Hong3, Sung Jin Kang4, Miyoung Kim4, and William Jo1,*

1Department of Physics, Ewha Womans University, Seoul, 120-750, Korea

2Department of Physics, Pusan National University, Busan 609-735, Korea3Department of Physics and Graphene Research Institute, Sejong University, Seoul

143-747, Korea4Department of Materials Science and Engineering, Seoul National University, Seoul,

Korea

The layered perovskite PbVO3 (PVO) is an intriguing polar magnetic material because its

strong tetragonal distortion (c/a=1.229) allows VO5 square-pyramidal structure rather than VO6

octahedron. Its unique feature exhibits the 2-dimensional antiferromagnetic (AFM) ordering and large

pyroelectric polarization [1]. It is notable that the c-axis of the PVO films is abnormally elongated

more than 5% on the well-lattice matched LaAlO3 (LAO) substrates [2]. In this study, the phase

formation and structural properties of epitaxial PVO thin films on various crystal substrates,

including SrTiO3 (STO) (001) and LAO (001), were investigated under several deposition condition

ssuch as Ar:O2 ratio, ambient pressure and laser fluence. Restrained oxygen gas is critical during

the deposition process to form the tetragonal PVO (001) thin films with 4-fold in-plane epitaxy on

STO (001) and LAO (001). It is found that c-axis lattice parameter is elongated from 4.67 to 5.02

Å, which is dependent on growth conditions. Theoretical and experimental studies on the phonon

spectra yield insights on the strained structures which V-O1 bondings near 950 cm-1 are separated

into an antisymmetric and asymmetric mode, based on C-AFM structure. Compositional analysis as

well as first-principles calculations suggest a model that V ions occupy in Pb-vacant sites in the

perovskite cell. Due to the enduring tetragonality of the strained structure, PVO will be a candidate

for platform of new multiferroic compounds with mixed with other transition metals.

[1] A. Kumar et al., Phys. Rev. B 75, 060101 (2007).

[2] S. H. Oh et al., J. Phys. D: Appl. Phys. 47, 245302 (2014).




O3

20:10 ~ 20:25, February 1

Oxygen octahedral rotation angle of BiFeO3 films depending on structural

modulation of SrRuO3 bottom electrode layer

S. S. Lee1, T. Y. Koo2, J.-Y. Kim2, and J. Y. Jo1*

1School of Materials Science and Engineering, Gwangju Institute of Science and

Technology, Gwangju 500-712, Republic of Korea.2Pohang Accelerator Laboratory, Pohang University of Science and Technology

(POSTECH), Pohang 790-784, Republic of Korea

Oxygen octahedral rotation of multiferroic BiFeO3 (BFO) has attracted great attentions due to

its effects to electrical and magnetic properties. Octahedral rotation at interface between BFO and

electrode layer remains unexplored. Recently, there has been a report on the control of octahedral

rotation in SrRuO3 (SRO) film on SrTiO3 (001) substrate by controlling the oxygen pressure

during growth.1 Here we demonstrate that the octahedral rotation angle of BFO film is changed

using tetragonal a0a0c tilted-SRO bottom electrodes. In this work, BFO/tetragonal-SRO and

BFO/monoclinic-SRO heterostructures were fabricated to (001)-oriented SrTiO3 substrates at different

oxygen pressures using a pulsed laser deposition technique. The rotation pattern of FeO6 and the

structural symmetry were identified from half-integer reflections using high-resolution X-ray

diffraction technique. The effects depending on octahedral tilting of BFO films on the magnetic and

ferroelectric properties will be presented.

References1Wenlai Lu, Ping Yang, Wen Dong Song, Gan Moog Chow, and Jing Sheng Chen, Phys. Rev. B. 88,

214115 (2013)




O4

09:40 ~ 09:55, February 2

Creep-free ac dynamics in epitaxial ferroelectric BiFeO3 films

Y. J. Shin1,2,*, B. C. Jeon1,2, S. M. Yang1,2, I. Hwang3, M. R. Cho2, D. Sando1,2,

S. R. Lee1,2, J.-G. Yoon4, and T. W. Noh1,2

1Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-747,

Republic of Korea2Department of Physics and Astronomy, Seoul National University, Seoul 151-747,

Republic of Korea3Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul

136-791, Republic of Korea4Department of Physics, University of Suwon, Hawseong, Gyunggi-do 445-743, Republic

of Korea

The switching properties in ferroelectric (FE) films are mainly determined by dynamics of

domain wall (DW) under applied electric field (E). Especially, at finite temperature (T), thermally

activated creep-motion contributed significantly to the DW motion. Many of switching properties of

FE at finite T can only be understood by introducing the creep motion. In spite of such

importance, however, there have been little studies on creep motion under ac-driven force. Here, we

investigate ac-driven hysteretic dynamics of ferroelectric (FE) domains in high quality epitaxial

BiFeO3 (BFO) thin films by frequency (f) dependent P-E hysteresis loops and other switching

characters. Although BFO films are we identically fabricated on different bottom electrodes,

La0.67Sr0.33MnO3 (LSMO) and SrRuO3 (SRO), only BFO/SRO shows nearly creep-free hysteretic

dynamics. We found that such intriguing result comes from the different surface morphology

induced by distinct nature of bottom electrodes and resulting inhomogeneities of internal E.




O5

09:55 ~ 10:10, February 2

Reversible Three Out-of-plane Ferroelectric States in BiFeO3 Thin Films

J. H. Lee1*, K. Chu1, K.-E. Kim1, J. Seidel2, and C.-H. Yang1,3

1Department of Physics, KAIST, Daejeon 305-701, Republic of Korea2School of Materials Science and Engineering, University of New South Wales, Sydney,

New South Wales 2052, Australia3KAIST Institute for the NanoCentury, KAIST, Daejeon 305-701, Republic of Korea

Existing multi-level polarization devices have been based on the rigorous control of 180°

domain switching between two polarizations (“up” and “down”). However, as a new concept of

multi-level polarization devices, non-180° domain switching has not been utilized since it increases

the local elastic energy around the switching domains by making unstable ferroelectric domain

walls. In this presentation, we report on a discovery of non-180°-type out-of-plane (OOP) three-step

switching in BiFeO3 (BFO) thin films deposited on (110)pc-oriented GdScO3 substrates. We realized

an prototype of OOP-three-level system through electric-field-switching experiments using

piezoresponse force microscopy (PFM). We constructed a simple theoretical model based on the

phenomenological Landau theory for a better understanding of the observed three-step switching. In

addition, slow-scan-direction-dependent PFM poling experiments showed the switching characteristics

of the (110)pc-oriented BFO system, and the result agreed with the theoretical expectation from our

model. Our results open an opportunity to materialize three-level memory devices which use the

missing “middle” state.




O6

11:10 ~ 11:25, February 2

Freestanding ZnO Nanorode/Graphene/ZnO Nanorod Epitaxial Double

Heterostructure for Improving Piezoelectric Nanogenerator

Dong-Myeong Shina, Ermias Libnedengel Tsegea, Seok Hee Kangb, Wanchul Seungc,

Sang-Woo Kimc, Hyung Kook Kima, Suck Won Hongb,*, and Yoon-Hwae Hwanga,*

a Department of Nanomaterials Engineering & BK21 Plus Nanoconvergence Technology

Division, Pusan National University (PNU), Miryang 627-706, Republic of Korea

b Department of Cogno-Mechatronics Engineering, Pusan National University (PNU),

Busan 609-735, Republic of Korea

c SKKU Advanced Institute of Nanotechnology (SAINT) & Center for Human Interface

Nanotechnology (HINT), SKKU-Samsung Graphene Center, Sungkyunkwan University

(SKKU), Suwon 440-746, Republic of Korea

We present a simple strategy for fabricating the freestanding ZnO nanorod/graphene/ZnO

nanorod epitaxial double heterostructure. The characterization of the epitaxial double heterostructure

by using SEM, and Raman scattering spectroscopy reveals the key process and working mechanism

of a formation of the heterstructure. The mechanism is discussed in detail in term of the

decomposed seed layer and the vacancy defect of graphene. The resulting improvement in the

number density of nanorods has a direct beneficial effect on the double side heterstructured

nanogenerator performance. The total electrical outputs are improved up to ~ 2 times compared to

those of a single heterostructure due to the coupling of the piezoelectric effects from both upward

and downward grown nanorods. The facile one-step fabrication process suggests that epitaxial

double heterostructure would improve the performance of electrical and optoelectrical device, such

as touch pad, pressure sensor, biosensor and dye-sensitized solar cells.

*E-mail: [email protected] (S.W. Hong), [email protected] (Y.-H. Hwang)



O7

11:25 ~ 11:40, February 2

Applications of Transmission Line Impedance Models in Materials Research

Focusing on Energy Devices

Eui-Chol Shin, Jong-Sook Lee*

School of Materials Science and Engineering, Chonnam National University, Gwangju

500-757, Korea

Transmission line impedance models for the distributed circuit elements in electrical engineering

can represent the diffusion process involved in many energy devices such as fuel cells, batteries,

and solar cells, which often critically determines the performance. Although impedance spectroscopy

is widely applied, transmission line models appear to remain mystified and insufficiently utilized

and ubiquitous presence seems to cause further confusion. 1) We have successfully applied them to

the porous gas electrode kinetics of high temperature solid oxide fuel cells for the evaluation of the

surface diffusivity and dissociative adsorption/desorption reaction according to non-faradaic chemical

reaction model by Mizusaki, distinguished from the gas phase diffusion, for both oxygen and

hydrogen electrodes. The process turns out to be in exact analogy to the diffusion-recombination

process in DSSCs. 2) The chemical diffusion and reaction in particulate active cathode materials of

lithium ion batteries needs a spherical (3-D) solid-state diffusion model incorporated into the 1-D

porous electrode model. Modeling of parallel solid state reaction paths deconvoluted the kinetic

parameters according to the nanocomposite model in high energy layered oxide materials. 3)

Generalized transmission line model for mixed conductors by Jamnik and Maier has been

successfully applied to the olivine-type electrode material for the evaluation of ionic and electronic

conductivity as well as the chemical diffusivity. 4) Pneumatochemical impedance derived by the

Laplace transform of the hydrogen storage kinetics monitored by Sievert’s setup is characterized by

the inductive loop and the oscillation. 5) Dispersive AC response of the percolative conductive

network in the insulating matrix, often discussed as electron diffusion kinetics of electrons, should

be interpreted as purely electrical transmission line network, where the capacitance parameter can be

related to the microstructural distribution.




O8

11:40 ~ 11:55, February 2

Low operation voltage of ferroelectric polymer devices induced by X-ray

irradiation-mediated structural transition

H. J. Lee1, O. W. Kwon2, J. H. Kim1, J. W. Kim3, H. J. Lee1, J. H. Kwak1, J. M.

Kim1, Y. S. Kim2, D-Y. Kim1, and J. Y. Jo1*


Technology, Gwangju 500-712.2School of Advanced Materials Science and Engineering, Sungkyunkwan University

(SKKU), Suwon, Gyeonggi-do 440-746.3Pohang Accelerator Laboratory, Pohang 790-834 .

Ferroelectric polymer, poly(vinylidene fluoride-trifluoroethylene)[P(VDF-TrFE)], has attracted a

lot of interest for applications including non-linear capacitors, non-volatile memories, and field effect

transistors. The higher coercive field in comparison to inorganic ferroelectrics is the most important

problems to design devices which can operate with a high switching speed at a low voltage

operation. A reduction of film thickness has been simply suggested to reduce the coercive voltage.

However, a thin film with a thickness less than 100 nm does not only increases leakage current,

but also still shows an increase of coercive voltage above 80 Hz. In this study, we achieved the

reduced coercive field with introducing non-polar phase using X-ray irradiation onto P(VDF-TrFE).

P(VDF-TrFE) films on ITO/glass were irradiated with hard X-rays at 5D beam line (10 keV)

of Pohang Accelerator Laboratory. We controlled the phase transition by varying an irradiation time

and an X-ray photon flux. The phase transition became significant with X-ray irradiation time after

500 sec. We observed irreversible phase transition from ferroelectric β to non-polar α phase of

P(VDF-TrFE) via X-ray irradiation. Finally, we found that coercive voltage was reduced by 47%

after the irradiation..




O9

11:55 ~ 12:10, February 2

Why no ferroelectricity in polar piezoelectric GaFeO3?

Seungwoo Song1* and Hyun Myung Jang1,2

1Division of Advanced Materials Science(AMS) and Department of Materials Science and

Engineering, Pohang University of Science and Technology(POSTECH), Pohang 790-7842Department of Physics, Pohang University of Science and Technology (POSTECH),

Pohang 790-784

Gallium ferrite (GaFeO3) has been extensively studied by virtue of its well-known room-temperature piezoelectricity and magnetoelectric coupling at low temperatures. GaFeO3

possesses an orthorhombic non- centrosymmetric symmetry with the space group Pna21 (or Pc21n). Thus, it is expected to show ferroelectricity at room temperature. Until now, however, there is no direct evidence of the ferroelectricity or the existence of high-temperature prototypic phase (paraelectric) in GaFeO3.

In the present research, we have deposited GaFeO3 thin film on a hexagonal SrTiO3(111) substrate by employing pulsed laser deposition (PLD) to obtain a strain-free high-crystalline thin-film form. Using diffraction and microscopy methods, we confirm well-ordered multi-structures of GaFeO3/SrRuO3(111)/SrTiO3(111) with the polar c-axis along the growth direction. To investigate piezoelectric and ferroelectric responses of GaFeO3 films, we adopt dynamic contact electrostatic force microscopy (DC-EFM) method which is identical to piezoelectric force microscopy (PFM) in terms of the bias application and signal detection. Although we are able to switch the piezoelectric phase of a particularly chosen region by applying a negative-to-positive alternative bias voltage (up to ±10V), the switched piezoelectric phase returns to the initial (unswitched) state as soon as we turn off the external bias. These observations clearly indicate that the measured piezoelectric-phase switching do not show any evidence of the ferroelectricity but demonstrates the existence of piezoelectricity in the polar-axis-oriented GaFeO3 film.

In order to theoretically support the experimental results, we have carried out density-functional theory (DFT) calculations by systematically displacing the Ga-ion which is known to be responsible for manifesting piezoelectricity. By performing lattice dynamics calculations using the Bilbao crystallographic sever, we have found that the space-group symmetry corresponding to the centro-symmetric prototypic phase of GaFeO3 is Pnna and the Pnna-to-Pna21 phase transition (for manifesting piezoelectricity) is mediated solely by the polar Γ4

- normal mode. On the basis of DFT calculations, we conclude that the difficulty of observing ferroelectricity in the polar Pna21 GaFeO3 mainly originates from the exceptionally high potential-energy barrier between the two degenerate polar ground states. This clearly elucidates the observed piezoelectricity as well.



ABSTRACTS

Poster Session

강유전체 연합 심포지엄 포스터 발표2015. 2. 2(월, 16:30~18:00), 무주리조트 카니발 컬쳐 팰리스 지하1층 로비

P-1

Dependence of electrical properties of Sol gel derived PZT thick films on

crystalline orientation

V. Annapu Reddy1*, Jong-Jin Choi1, Jungho Ryu,

1Korea Institute of Materials Science (KIMS), Changwon 642-831

The effects of crystalline orientation on the electrical properties of lead zirconate titanate (PZT)

thick films (over 2 -thick) deposited by the sol-gel method have been studied. The orientation

and microstructure of the thick films were characterized by X-ray diffraction (XRD) and scanning

electron microscopy analysis. XRD results indicate that the strong [111]- or [100]-preferred

orientation of the PZT thick films could be observed by controlling the pyrolysis conditions after

spin-coating. The texture was mainly [111]-orientation for pyrolysis temperatures from 330 to 400

°C, and changes to [100]-orientation for pyrolys is temperatures at or above 450°C after annealing

at 650°C for 5 min. The formation of preferred orientation could be considered from the results of

migration speed of deposited species and internal strain energies between the substrate and the film.

Different crystalline orientations also lead to change in electrical properties such as dielectric

constant, polarization values, leakage current and fatigue behavior.




P-2

Enhanced magnetoelectric coupling in a PZT/Metglas bilayer

thick film composite

Haribabu Palneedi1,2, Deepam Maurya3, Shashank Priya3, Suk-Joong L. Kang1*,

Si-Young Choi4, and Jungho Ryu2

1 Materials Interface Laboratory, Department of Materials Science and Engineering,

Korea Advanced Institute of Science and Technology (KAIST), Daejeon.2 Functional Ceramics Group, Korea Institute of Materials Science (KIMS), Changwon.

3 Center for Energy Harvesting Materials and Systems (CEHMS), Virginia Tech,

Blacksburg, VA, USA4 Advanced Characterization and Analysis Group, Korea Institute of Materials Science

(KIMS), Changwon, Korea

We studied magnetoelectric (ME) coupling in a bilayered lead zirconate titanate (PZT)/Metglas

(FeBSi) thick film composite. A unique approach involving room-temperature coating (GSV; Granule

Spray in Vacuum) and localized annealing (laser irradiation) of PZT films was adopted to address

problems involved in the processing of PZT/Metglas film-based ME composites. Very strong ME

interactions between PZT and Metglas resulted in an extremely high ME coefficient of 2790

mV/cmOe under a low-bias magnetic field (HDC = 60 Oe) and in an off-resonance (f = 1kHz)

condition. The ME coefficient obtained in this study was two orders of magnitude larger than that

reported for PZT/Metglas film composites. The results of dielectric, ferroelectric, and optical

measurements and microstructural observations of this PZT/Metglas composite were also in line with

the significantly enhanced ME coefficient. The current fabrication approach can be exploited for

tuning the ME properties of film composites and can be extended to other piezoelectric/magnetic

composite systems as well. This study opens up new possibilities in designing laminate composites

which would be suitable for various ME device applications.

*E-mail :[email protected]



P-3

Enhanced polarization of hard polar phases in a heterphase polycrystalline

G. Y. Kim1, S. D. Kim1, Y. M. Rhyim1, S. Y. Yoon2 and S. Y. Choi1*

1Advanced Characterization and Analysis Group, KIMS, Changwon, 642-8312School of materials Science and Engineering, Pusan National University, Busan,

609-785

Polar and non-polar phase composite has the various advantages in terms of piezoelectricity,

such as easy polarization switching, high polarization saturation (Ps), and large electrostrain. To this

end, we fabricated the composite polycrystalline of the polar and non-polar phases and observed the

antiferroelectric-like polarization behavior, which is obviously different to single the non-polar phase

(Bi0.5(Na0.75K0.25)0.5TiO3 BiAlO3) or polar phase (Bi0.5(Na0.8K0.2)0.5TiO3). In this composite, the

keypoint was to activate the ferroelectric polar phases with a high coercive field (Ec) at the low

external electric field (< 2 kV/mm). Therefore, in this study, we aimed to directly visualize the

polarization of the polar phase via transmission electron microscopy (TEM). First of all, TEM

micrographs and selected area electron diffractions patterns (SADPs) show the polar phase exists as

a core in the grain interior surrounded by the non-polar phase shell. The in-situ electric biasing

TEM experiments confirm that the ferroelectric domains in the polar phase are aligned even under

a low external field of 1 kV/mm. This unique polarization behavior of the polar phase is due to

the augmented internal electric field from non-polar phase under the electric biasing and can be

verified by simple modeling system based on the dielectric divergence in the heterophase structure.

AcknowledgementThis research was supported by Global Frontier Program through the Global Frontier Hybrid Interface Materials(GFHIM) of the National Research Foundation of Korea(NRF) funded by the Ministry of Science, ICT & Future Planning (2013M3A6B1078872).




P-4

Temperature Dependance of Magnetic Domains in Co2Z-type Hexaferrite: TEM

Studies by In-situ Heating and Lorentz Microscopy Methods

Sung-Dae Kim1*, Tae-Won Lim1,2, Gi-Yeop Kim1,3, Kee Hoon Kim4

and Si-Young Choi1

1Advanced Characterization and Analysis Group, Korea Institute of Materials Science

(KIMS), Changwon 642-8312Department of Nano Science and Engineering, Kyungnam University, Chanwon 631-701

3School of Materials Science and Engineering, Pusan National University, Pusan 609-7354Department of Physics and Astronomy, Seoul National University, Seoul 151-747

In the past decades, there has been a huge revival of interest in multiferroics, wherein magnetism and ferroelectricity coexist [1-3]. However, it was proved to be a difficult problems to find plausible candidates having strong magnetoelectric (ME) coupling at moderate operating temperature. Recently, this long-standing challenges have been overcome by discovering the Co2Z-type hexaferrite (Ba, Sr)3Co2Fe24O41 containing a unique spin structure in room-temperature [4-5]. The Co2Z-type hexaferrite contains the net magnetic moments in alternating large and small blocks along the c-axis. The strong ME effects of the Co2Z-type hexaferrite can be understood in terms of a transverse conical spin configuration of the magnetic building blocks at room-temperature, through the inverse Dzyaloshinskii-Moriya (DM) mechanism. Hence, the magnitude and direction of the net magnetic moment, according to the operating temperature (T) and applied magnetic field (H) range, is the key parameter for the realization of the promising ME effects. Consequently, T-dependent magnetic structures of the Co2Z-type hexaferrites were examined by neutron diffraction studies [3,6], providing a detailed informations about the transition temperature of the spin configurations. In the present study, we visualized the T-dependent magnetic domain structures in a Co2Z-type hexaferrite Ba0.52Sr2.48Co2Fe24O41, to achieve more clear understanding of thermally activated dynamics of the magnetic moment, via in-situ heating transmission electron microscopy combined with the Lorentz microscopy method. A series of the defocused Fresnel images with continuous temperature ramping was taken, showing the magnetic moments rotation dynamics and its transition temperature. Also, the direction of the magnetic moments was clearly defined by magnetization distribution maps, calculated using a phase reconstruction technique based on a transport-of-intensity equation (TIE).

[1] Sang-Wook Cheong and Maxim Mostovoy, Nature Mater. 6, 13 (2007).[2] Shintaro Ishiwata et al., Science 319, 1643 (2008).

[3] Minoru Soda et al., Phys. Rev. Lett. 106, 087201 (2011).

[4] Yutaro Kitagawa et al., Nature Mater. 9, 797 (2010).

[5] Sae Hwan Chun et al., Phys. Rev. Lett. 108, 177201 (2012).

[6] Yukio Takada et al., J. Appl. Phys. 100, 043904 (2006).





P-5

Electric and structural properties in polar/non-polar multilayers.

Kil-Dong Sung1*, Gi-Yeop Kim1,2, and Si-Young Choi1

1Advanced Characterization and Analysis Group,

Korea Institute of Materials Science (KIMS), Changwon 641-8312School of Materials Science and Engineering, Pusan National University, Pusan 609-735

To fabricate ferroelectric devices even sensitive to the low electric field, researchers have tried

to fabricate the ferroelectric oxides in various types that exhibit the low electric coercive field

together with the large electric polarization. In this poster, we propose that a ferroelectric layer

sandwiched by two high-k layers can effectively reduce the coercive electric fields, hence improve

the ferroelectric effects. To this end, we deposited SrTiO3/PbTiO3/SrTiO3/SrRuO3 multilayers on

SrTiO3 substrates by a pulsed laser deposition technique. The thin films show clear interfaces with

epitaxial crystal structures, and significant reductions of electric coercive fields with almost same

remnant electric polarization values of bare PbTiO3 thin films. In addition, in-situ transmission

electron microscopy results show that as-grown PbTiO3 ferroelectric multi-domains start to switch

and finally become a ferroelectric mono-domain at lower external electric fields, compared to the

PbTiO3/SrRuO3 on SrTiO3 substrate without high-k layers. To understand the phenomena we

calculated effective electric fields of the PbTiO3 layer as well as induced interfacial electric

polarizations. Our results imply that the diverse dielectric constants between polar and non-polar

layers in combination with the heteroepitaxial film growth could result in an important key role in

fabricating the ferroelectric devices sensitive to the low electric field.





P-6

Cationic ordeirng and magnetic properties of Re-based double perovskite oxides

T. W. Lim1,2, S. D. Kim1, K. D. Sung1, H. J. Jean3, J. D. Yun2, M. S. Choi1

and S. Y. Choi1*

1. Korea Institue of Materials Science, Changwon 642-831, Korea2 Department of Nano science and Engineering, Kungnam University, Changwon

631-701, Korea3 Department of Physics, Pusan National University, Busan 609-785, Korea

Ferromagnetic double perovskites have recently attracted great attention due to their presumed

half-metallicity as well as high curie temperature. Cationic ordering in two Re-based double

perovskites Sr2FeReO6 (SFRO) and Sr2CrReO6 (SCRO) is investigated in a viewpoint of antisite

defect (AS) through combination of experiments and first principles calculations. To control the

cationic ordering, SFRO-xRe (0 mol% - 15 mol%) and SCRO-xRe (0 mol% - 10 mol%)

solid-solution samples were synthesized by conventional solid-state method. From the fabricated

samples, we selected SFRO and SCRO samples with the similar cationic disordering but we found

that atomic structural array of ASs behaves different in SFRO and SCRO. Antiphase-boundary-like

feature, due to the preferentially clustering interaction of ASs, forms in the SFRO samples, whereas

the ASs are spatially distributed in the whole sample of SCRO. Futhermore, we observed that the

clustered ASs in a form of antiphase-boundary more largely deteriorate ferromagnetism, indicating

that the array behavior as well as the amount of atomic defects are important keys to affect the

physical properties.

Acknowledgement

This research was supported by Global Frontier Program through the Global Frontier Hybrid

Interface Materials(GFHIM) of the National Research Foundation of Korea(NRF) funded by the

Ministry of Science, ICT & Future Planning (2013M3A6B1078872).




P-7

Growth and Characterization of LaAlO3 Thin Films Grown by off-axis RF

Sputtering

D. H. Kim1, C. W W. Bark1*,

1Department of Electrical Engineering, Gachon University,San 65, Bokjeong-dong,

Sujeong-gu, Seongnam, Gyeonggi-do, 461-701, Republic of Korea

In recent years a conducting state was reported at the interface between the two band

insulators, LaAlO3(LAO), and SrTiO3(STO).This discovery of a two-dimensional electron gas

(2DEG) has brought about innovative applications in the area of nanoscale oxide devices. Currently,

pulsed laser deposition (PLD) is the dominant deposition technique used for creating oxide

interfacial 2DEG hetero structures. However, PLD is not suitable growth technique for the device

application due to its small deposition area (~5 mm x 5mm). On the other hand, 90° off-axis

sputtering is a scalable process that has been shown to create smooth, epitaxial films that are

uniform over a large area.

Here by, we report the Growth and chracterization of the LaAlO3 on SrTiO3 substrate using by

RF sputtering which allows uniform films over a large area. Unlike typical RF sputtering, we used

90° off-axis sputtering which enables fabrication of high quality LAO films without secondary phase

particles. The electrical transport properties of the LaAlO3/SrTiO3 heterointerface are similar to those

grown by pulsed laser deposition(PLD).

Thus, we investigated growth condition of LaAlO3/SrTiO3 heterointerface using 90° off-axis RF

sputtering to fabricate high quality LaAlO3 thin film with different regime of growth conditions.

*E-mail : [email protected] Phone : 031-750-5351


P-8

Synthesis and characterization of UV treated bismuth titnate doped TiO2

M. G. Song1, and C W bark1*

1Department of Electrical Engineering, Gachon University, 1342 Seongnam-daero,

Seongnam-si, Gyeonggi-do 461-701, Korea

The wide band gap of complex oxides has limited their use in photovoltaic cells. To tune the

bandgap of complex oxides, nano-sized bismuth titanate powders were prepared by a high-energy

ball milling process for optoelectric applications. However, the bismuth titnate mixed TiO2 can be

easily separated on the FTO glass during the spin coating. A remarkable surface wettability

transition can be easily achieved by ultraviolet(UV) illumination. To avoid the separation problem,

we were treated bismuth titanate by using ultraviolet(UV) to change the wettability between

hydrophilic abd hydrophobic of bismuth titanate. This study described the synthesis and

characterization of UV treated bismuth titanate doped TiO2.


Contact Phone : +82-31-750-5351


P-9

Effect of Yb doping on the multiferroic properties of epitaxial BiFeO3 thin

films

Yoonho Ahn,1 Jeongdae Seo,1 Jong Yeog Son1,* and Joonkyung Jang2,*

1Department of Applied Physics, Kyung Hee University, Yongin 446-701

2Department of Nanomaterials Engineering, Pusan National University, Busan 609-735

We report the enhanced multiferroic properties of a ytterbium (Yb)-doped BiFeO3 thin film

(Bi0.85Yb0.15FeO3) deposited on a (001) SrRuO3/(100) SrTiO3 substrate by pulsed laser deposition.

The crystal structure, surface morphology, ferroelectric domain structure, and the electrical and

magnetic behavior of the epitaxial Bi0.85Yb0.15FeO3 film, 100 nm in thickness, were investigated. The

results were compared with those of an undoped BiFeO3 thin film. The x-ray diffraction patterns

showed that both films have tetragonal-like crystal structures. Atomic force microscopy showed that

the Bi0.85Yb0.15FeO3 and BiFeO3 films have flat and clear surface steps, characteristic of a

layer-by-layer growth mechanism. Furthermore, the strip-like ferroelectric domain structures were

clearly observed in piezoelectric force microscopy. The Bi0.85Yb0.15FeO3 films had significantly

higher remanent polarization of approximately 73 μC/cm2 and lower leakage current compared to

the BiFeO3 thin film. Ferromagnetic enhancement was also observed in the Bi0.85Yb0.15FeO3 film at

room temperature.

*E-mail : [email protected], and [email protected]



P-10

Source Concentration and Temperature dependence of Microstructure and

Properties of ZnO thin films deposited by MOCVD using Ultrasonic

Nebulization

C. H. Lee*, M. S Choi

Department of Materials Engineering, Keimyung University, Daegu 704-701

ZnO, which has hexagonal wurtzite structure, is a piezoelectric material and a wide band gap

semiconductor. Thin films of pure or doped ZnO are used in SAW filter, transparent electrode, and

transparent transistor. Generally it is made by sputtering and there are some reports on the

deposition by ALD or PLD. However there are few reports on the deposition of ZnO thin films by

CVD which has many advantages such as high deposition rate, uniform deposition in large area,

high step coverage, etc.. This seems to be due to the rarity of zinc compound applicable to CVD

source. Recently we have reported that ZnO thin films were deposited on soda lime glass substrates

at the low substrate temperatures of 225 350 by MOCVD using ultrasonic nebulization, using

zinc acetylacetonate as a precursor for Zn source, which is not appropriate to the source material in

the usual CVD. In this work, the effects of source concentration and deposition temperature on the

microstructure and properties of films were investigated.

Source concentration and/or deposition temperature affect largely on the rate and mechanism

of film growth. At the condition of high source concentration and low deposition temperature very

small nano-sphere crystallites of about 20 nm diameter were formed compactly on the substrate

surface at the early stage of deposition. And then new nuclei, which successively formed on these

crystallites, coalesced to form columnar grains with a plate-pillar structure. This columnar formation

may have resulted from the supersaturation of the reactant gas adsorbed on the surface because the

surface chemical reaction rate was lower than the mass transfer rate. These films had some open

spaces between the columnar grains and the grain size at the surface increased with film thickness.

On the contrary, at the condition of low source concentration and high deposition temperature

islands of crystallites with the shape of a hexagonal pyramid were formed on the substrate surface

scatteredly at the early stage of deposition and they grew to form a connected thin film with a

large grain size at about 100 nm thickness. Then the film grew to form a dense rock-like structure.

This difference in microstructure resulted in the difference in electrical conductivity of films.




P-11

Effect of Bi(Ni0.5Ti0.5)O3 doping on structural and piezoelectric properties of

BiFeO3-BaTiO3 ceramics

I. J. Hwang1, D. Do1*, M. H. Lee2, J. S. Park2, D. J. Kim2, T. K. Song2, M.-H. Kim2,

S. W. Kim3 and W.-J. Kim3

1Department of Advanced Materials Engineering, Keimyung University, Daegu 704-7012School of Materials Science Engineering, Changwon National University, Changwon

641-7733Department of Physics, Changwon National University, Changwon 641-773

Piezoelectric ceramics are widely used for electromechanical systems such as sensors and

actuators. High-temperature piezoelectric ceramics are, particularly, required in the automotive,

aerospace, and energy industries. However, traditional lead-free piezoelectric ceramics including

(Bi,Na)TiO3, (Bi,K)TiO3, (K,Na)NbO3 systems cannot operate at high temperature although a

remarkable improvement in piezoelectric properties is achieved. Recently, lead-free

(1-x)BiFeO3-xBaTiO3 systems with high Curie temperature and a morphotropic phase boundary with

the coexistence of both rhombohedral and cubic phases at x=0.33 have been introduced [1].

Although many studies have been performed in (1-x)BiFeO3-xBaTiO3 systems, almost no study has

been done on 0.67BiFeO3-0.33BaTiO3. In this study, structural and piezoelectric properties of

(1-x)(0.67BiFeO3-0.33BaTiO3)-xBi(Ni0.5Ti0.5)O3 (x=0, 0.01) ceramics were studied. By substitution of

the small amount of Bi(Ni0.5Ti0.5)O3, reduced average grain size and improved piezoelectric

properties were observed. Direct and converse piezoelectric coefficient of

0.99(0.67BiFeO3-0.33BaTiO3)-0.01Bi(Ni0.5Ti0.5)O3 ceramics were 165 pC/N and 300 pm/V,

respectively. Also observed Curie temperature was 455 . This result indicates that

0.99(0.67BiFeO3-0.33BaTiO3)-0.01Bi(Ni0.5Ti0.5)O3 ceramics can be one of the promising candidates

for a high Curie temperature lead-free piezoelectric ceramics.

[1] M. Mahesh Kumar et al., J. Appl. Phys. 87, 855 (2000).




P-12

Growth of graphene using pulsed laser deposition technique with in-situ

monitoring by reflection high energy electron diffraction

J. H. Kwak1, H. J. Lee1, S. S. Lee1, G. Anoop1, and Ji Young. Jo1*

1 School of Materials Science and Engineering, Gwangju Institute of Science and

Technology, Gwangju 500-712, Republic of Korea.

Graphene has attracted considerable attention due to its outstanding properties such as high

carrier mobility and transparency. One of the most common methods to grow the graphene is

chemical vapor deposition synthesis on the metal catalytic films. However, it requires additional

transfer process onto desired substrate. It is inevitable to generate structural defects such as wrinkle

and crack or surface contaminations resulting in degradation of electrical properties. In this

presentation, we show that pulsed laser deposition (PLD) technique with reflection high energy

electron diffraction (RHEED) can be used to grow the graphene films on the substrate directly.

A few-layer nanocrystalline graphene was grown on the AlN/Si substrate without metal catalyst

films through the laser ablation of highly ordered pyrolytic graphite target at substrate temperature

of 700 ~ 850 . Base and working pressure of process chamber were maintained around 10-7

torr. A KrF excimer pulse laser with an energy 175 mJ was used. Structural characteristics were

investigated by RHEED, micro-Raman spectroscopy, scanning electron microscope, and X-ray

photoemission spectroscopy. The electrical properties were measured using Van der Pauw method.

The RHEED results correlated with Raman spectroscopy revealed that the mono-layer graphene

cannot be formed due to their high defect concentration, although the first layer on the substrate

was formed completely. However, a few-layer nanocrystalline graphene was formed with an increase

of growth time and temperature, which indicates structural quality to depend on growth time and

substrate temperature.




P-13

Synthesis of catalytic LaMnO3+d nanoparticles by laser ablation in solution

W. S. Kim1, G. Anoop1, H. J. Lee1, S. S. Lee1, J. H. Kwak1, H. J. Lee1,

and Ji Young Jo1*


Technology, Gwangju 500-712, Republic of Korea.

The catalysts play an important role in energy devices such as fuel cell and Li-air batteries.

The LaMnO3+d particles have been commonly used for catalyzing the oxygen reduction reaction due

to a high catalytic activity. Generally, in catalytic reaction, nanometer-sized (<10 nm) particles have

a large surface area which leads to a high catalytic efficiency. However, it is hard to achieve

nanometer-sized particles from typical chemical reaction synthesis. The laser ablation synthesis in

solution (LASiS), which is a simple, fast, and clean process, is suitable to achieve nanometer-sized

LaMnO3+d particles by controlling laser parameters. Also, graphitized carbon support provides a lot

of oxygen-containing functional groups (e.g., hydroxyl and carboxyl) on the carbon surface to be

active sites for the deposition of nanometer-sized LaMnO3+d particles.

The LaMnO3+d target was prepared using a solid state reaction with La2O3 and MnO2 powder

calcinated at 900 for 12 hours. A disk-pellet was made by cold isostatic pressure method. The

pellets were sintered at 1200 for 24 hours. The target soaked in various solutions including

distilled water, ethanol, and SDS aqueous was exposed to a KrF excimer pulse laser, which

produces a beam with a wavelength of 248 nm. In this work, laser fluence value is ranged from

0.5 to 1 J/cm2. Graphitized carbon black (GCB) powder is treated by using nitric acid and

ammonia in oil bath. Then, LaMnO3+d colloidal solution and treated GCB are mixed by typical

solution method. The structural characteristics were investigated by a scanning electron microscopy

and an X-ray diffraction instrument.




P-14

Superlattice of FeSexTe1-x superconductor thin films

S. Seo1, J. H. Kang2, C. B. Eom2, and S. Lee1*


Technology, Gwangju 500-7122Department of Materials Science and Engineering, University of Wisconsin-Madison, WI,

US 53706

In recent years, a huge effort has been devoted to understand the fundamental physical

properties and enhance superconducting properties of Fe based Superconductors (FeSC). Among

FeSC family, arsenic free and simple PbO-type structured FeSexTe1-x (FST) has attracted much

research interest. Many studies have been done to obtain higher critical current density (Jc) and

upper critical field (Hc2) by incorporating artificial pinning centers in FeSC thin films. In this study,

a number of oxide materials and undoped FeTe (FT) have been used an insertion layer material to

form superlattice with FST to obtain high Jc and Hc2. Among them, by using CeO2 which has

similar effective lattice constant and good chemical stability with FST, FST/CeO2 superlattice has

been successfully fabricated. The superlattice showed high Jc and Hc2 due to the generation of

effective pinning centers. Furthermore, we have fabricated FT/FST superlattice structure and also

found that pinning centers such as nano-particle arrays were generated at the interface between FT

and FST. We will discuss the structural properties and superconducting properties of FST/CeO2

superlattice and FST/FT(FeTe) superlattice grown on single crystal CaF2 substrates. These

superlattices show better superconducting properties than single layers without severe degradation of

superconducting transition temperature (Tc) and structural properties. The successful growth of

FST/oxide superlattice could give us the possibility to fabricate potential device such as FST

(superconductor) - CeO2 (oxide) - FST (superconductor) junction.




P-15

Band gap tunability of Fe, Co doped Bismuth Lanthanum Titanate thin films

deposited by PLD

H. An1, J. Y. Han2, C. W. Bark2, S. Lee1*

1Materials Science and Engineering, Gwangju Institute of Science and Technology,

Gwangju 500-7122Department of Electrical Engineering, Gachon University, Seongnam 461-701

Tunability of wide band gap in complex oxide is a major issue of the current photovoltaic

research field. Also, the photovoltaic effect for ferroelectric materials has attracted attention due to

effective ability of charge separation and collection. In this research, we have controlled the band

gap of ferroelectric Bi3.25La0.75Ti3O12 thin films through Fe, Co doping. The BLT and Fe, Co doped

BLT epitaxial thin films has been grown on SrTiO3(STO), LaAlO3(LAO) substrates by pulsed laser

deposition (PLD). The structural and optical properties were analyzed by X-ray diffraction,

Ultraviolet-visible absorption spectroscopy. Optical band gap of Fe doped BLT (BLFTO) epitaxial

thin films on STO was decreased from 3.4eV, which is the band gap of BLT, to 2.5eV.

Futhermore, when both Fe and Co were doped in BLT (BLFCTO), optical band gap was more

decreased to 2.05eV. We also observed optical band gap could be reduced depending on substrates,

which might be related with the strain status of thin films due to the lattice mismatch. Thus, by

using simple doping and strain engineering methods, band gap could be tuned easily. Therefore,

these approaches could be applied to energy applications and optoelectronic devices.




P-16

BaZrO3 incorporated Ba(Fe,Co)2As2 multilayer epitaxial thin films

J. Lee1, J. D. Weiss2, J. Jiang2, E. E. Hellstrom2, and S. Lee1*


Technology, Gwangju 500-7122Florida State University, Tallahassee, FL, US

Since the discovery of iron-based superconductors, epitaxial thin films have been successfully

grown by many groups and they have significantly advanced potential device applications and the

understanding of the fundamental physical properties of these new superconductors. In particular, we

recently have grown artificially engineered undoped BaFe2As2/Co doped BaFe2As2 compositionally

modulated superlattices structures produces ab-aligned nanoparticle arrays and self-assembled c-axis

aligned defects that combine to produce very large Jc and Hirr enhancements. Recently, it has been

reported that BaZrO3 could exist as the nano particle second phase in BaFe2As2 matrix since it is

chemically stable. We incorporated various mol % BaZrO3 in Co doped BaFe2As2 ceramic targets

and have grown BaZrO3 incorporated Co doped BaFe2As2 / undoped BaFe2As2 multilayer epitaxial

thin films by using pulsed laser deposition to maximize the pinning effect in BaFe2As2 system. We

will discuss the structural properties of BaZrO3 incorporated Co doped BaFe2As2 multilayer thin

films examined by X-ray diffraction and the superconducting transition temperature (Tc) and critical

current density (Jc).




P-17

Thermoelectric properties of organic multilayers

Hye Jeong Lee1, Hyeon Jun Lee1, Yong Jae Kim2, Eun Ji Lee2, Jae Yoo Choi3,

Hee Suk Kim3, and Ji Young Jo1*


Technology, Gwangju 500-712, Republic of Korea. 2 Graduate School of Analytical Science and Technology, Chungnam National University,

79 Daehakro, Yuseong-Gu, Daejeon 305-764, Republic of Korea.3 Photo-Electronic Hybrids Research Center, Korea Institute of Science and Technology

(KIST), 14-gil 5 Hwarang-ro, Seongbuk-gu, Seoul 136-791, Republic of Korea.

The high demand for converting natural and waste heat into electrical energy makes thermoelectric

generators attractive energy resources. As compared to inorganic thermoelectric materials, organic

thermoelectric materials, which are flexible, ecofriendly, highly elastic, and cost-effective, are promising

candidates for thermoelectric generators. However, low electrical conductivity and power factor of organic

thermoelectric materials have been obstacles for realization of practical device applications. In this study, we

propose a new strategy for enhancing the electrical conductivity and power factor of organic thermoelectric

materials by fabricating multilayer structure using two different conducting polymers-

Poly(3,4-ethylendioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and polyaniline doped with

camphorsulfonic acid (PANI-CSA). In the PEDOT:PSS/PANI-CSA multilayer structure, we found that the

multilayer structure for PEDOT:PSS/PANI-CSA enhances the conductivity as well as power factor in

comparison with PEDOT:PSS thin films due to charge diffusion from PANI-CSA to PEDOT:PSS and 2

dimensionional carrier movement.

At first, PANI-CSA film was deposited on the glass substrate followed by annealing at 50 for 1 hr

in N2 ambience. PEDOT:PSS film was deposited on top of the PANI-CSA film and then baked at 120

for 15 min in N2 atmosphere. The sample was immersed in DMSO for 20 min at 60 in air. The above

process was repeated from 1 to 5 times for fabricating multilayer structures, which are labeled as

n(PEDOT:PSS/PANI) with a repetition number n. Thickness of both PANI-CSA and PEDOT:PSS component

layer is around 20 nm, which was confirmed using transmission electron microscopy. We found that the

electrical conductivity and the power factor were increased from 1.1×103 S/cm and 23.92 μWm-1K-2 for

PEDOT:PSS single layer to 1.6×103 S/cm and 48.00 μWm-1K-2, for 5(PEDOT:PSS/PANI) layers, respectively.

Our study suggests that fabrication of multilayers with two different conducting polymers is a promising

technique to enhance the thermoelectric properties of organic materials




P-18

Ferroelectric Properties of PMT-PT ceramics modified with Bi2O3

G. B. Kim*

1Department of Applied Physics, Dankook University, Yongin 448-701

Ceramics samples of 0.65Pb(Mg1/3Ta2/3)O3-0.35PbTiO3 modified with Bi2O3 were prepared using

the columbite precursor method. Lead magnesium tantalate (PMT) is has an anomalously large

dielectric constant and a broad diffuse phase transition near -98 . On the other hand, lead

titanate (PT) is a normal ferroelectric exhibiting a sharp peak in dielectric constant and its Curie

temperatrue is about 490 . Ceramics samples of 0.65PMT-0.35PT closed to the morphotropic

phase boundary (MPB) was chosen in the resent work. The optimum conditions for obtaining

samples with high density and improved electric properties were the addition of 0.3 wt% Bi2O3.

The temperature dependent dielectric constant of the samples was measured as frequencies ranging

from 1 kHz to 100 kHz. The dielectric constant showed a broad maximum value in all

compositions. All the samples exhibited for the frequency dispersion behavior of the dielectric

constant. It is a characteristic of relaxor ferroelectrics. The pyroelectric coefficient and spontaneous

polarization were measured as temperature function. The composition with maximum pyroelectric

coefficient corresponds to the composition with maximum dielectric constant. The maximum

pyroelectric coefficient increased with increasing amounts of Bi2O3 up to 0.3wt% and thereafter

decreased up to 1.0wt%. The pyroelectric peak temperature is shifted to lower temperature with the

addtion of small amounts of Bi2O3.




P-19

Thermal Annealing Effects of Zn1-xLixO Grwon by So-Gel Method

J. W. Hyun*, G. B. Kim, J. H. Lee

1Department of Applied Physics, Dankook University, Yongin 448-701

Li-doped and axis orientated ZnO films that have useful optical and electrical properties

can be fabricated by the sol–gel method. The pure and Li-doped ZnO films were prepared by

the sol–gel process using zinc acetate dihydrate as a precursor, diethanolamine as a catalyst,

and lithium acetate dihydrate as a doping source. Films of Zn1-xLixO on Pt (Pt/Ti/SiO2/Si)

and Si substrates were annealed at various temperatures, and the effect of annealing on the

structural and optical properties of the films were studied. The Zn1-xLixO films on a Pt

substrate, which was annealed at 700℃ were also doped with various concentrations of

lithium acetate dihydrate, and the dielectric properties were measured. While highly c-axis

oriented ZnO films were successfully obtained on a Pt substrate, the ZnO film on a Si

substrate had a polycrystalline structure.

The optimal annealing temperature for the Zn0.99Li0.01O film on a Si substrate was also 700℃.

Phases of SiO2 and lithium silicate were also observed in Zn0.99Li0.01O films at annealing

temperatures of 800℃ and 900℃, respectively. When Zn1-xLixO films on Si and Pt substrates were

annealed at 700℃. The films with dopant concentrations of x= 0.2 and 0.5 were easily peeled off

from the substrates. In particular, the PtLi2O3 phase was observed in the Zn1-xLixO film on a Pt

substrate with the Li-doping concentration above x= 0.15. The PtLi2O3 phase resulted from the

reaction between the substrate (Pt) and the dopant (Li). The maximum remanent polarization of

0.25 μC/cm2 and the maximum dielectric constant of 18.01 were obtained for the Zn0.85Li0.15O film

on a Pt wafer.




P-20

Admittance Spectroscopy of the PbSc1/2Nb1/2O3 Polycrystalline Relaxor

Y. J. Kim*

General Education Center, Dankook University, Yongin 448-701

Complex admittance of PbSc1/2Nb1/2O3 as a function of temperature and frequency were

measured. The admittance spectroscopy of PbSc1/2Nb1/2O3 polycrystalline relaxor is in agreement

with broad distribution of relaxation phenomenon such as space charge and dipoles. Before Tm,

resonant frequency decreases with increasing temperature, on the other hand after Tm, resonant

frequency increases with increasing temperature. In addition, maximum admittance Y'(G) and

susceptance Y''(B) increase with increasing temperature. Strong frequency dependent of dielectric

constant is observed at temperatures near and below the Tm than at those above Tm. Moreover, the

nature of transition in the PbSc1/2Nb1/2O3 is suggested by the obvious thermal hysteresis between

heating and cooling dielectric constant curves. The value of critical exponent γ=1.15 and γ=1.61

showed an on cooling and heating treatments, respectively, indicating a broadened phase transition

for PbSc1/2Nb1/2O3 relaxor.




P-21

Effect of sintering temperature on electrical properties of Lead-free

(K0.5Na0.5)0.75Ag0.25NbO3 ceramics

J. D. Byun1, Y. J. Kim2 and J. W. Hyun1*

1Department of Applied Physics, Dankook University, Yongin 448-701, Korea2General Education Center, Dankook University, Yongin 448-701, Korea

In this research, the lead-free ferroelectric ceramics (K0.5Na0.5)0.75Ag0.25NbO3 has been prepared

by using solid-state synthesis. The effect of sintering temperature on electrical properties and

structural of (K0.5Na0.5)0.75Ag0.25NbO3 ceramics were studied. The mixed powder was sintered at 1100

~ 1150 for 4 hours after calcining at 800 for 3 hours. The temperature dependent of

dielectric constant in the (K0.5Na0.5)0.75Ag0.25NbO3 was measured at various frequencies. The

maximum dielectric constant (Kmax) depends on sintering temperature. The Kmax, from 7699 down to

4505 at various sintered samples. The maximum dielectric constant was 7699 at 326 in 1110

sintered sample. The surface morphology was measured by using field-emission scanning electron

microscopy and the crystal phase was examined by using X-ray diffraction.




P-22

Highly Durable Ti-mesh Based Triboelectric Nanogenerator for Self-Powered

Device Application

Ermias Libnedengel Tsege1, Dong-Myeong Shin1, Seunghun Lee2, Hyung-Kook Kim1,*

and Yoon Hwae Hwang1,*

1 Department of Nanomaterials Engineering & BK21 Plus Nanoconvergence Technology

Division,Pusanational University (PU), Miryang 627-706, Republic of Korea2 The Institute of Basic Science, Korea University, Seoul, 136-713, Republic of Korea

We developed a highly durable Ti-mesh based triboelectric nanogenerator(Ti-TENG) with

sandwiched structure to harvest electrical energy from contact electrification. The electrical output

from the fabricated Ti-TENG via compressing and releasing strain was measured under different

applied loads and frequencies. The Ti-TENG could generate a peak voltage and current up to ~1.1

V and ~14 nA at an applied force of 30N and frequency of 1.1Hz. The obtained potential was

used to charge a capacitor and light up a commercially available LED. In particular, the Ti-TENG

which exhibited high electrical stability can be used in applications where high robustness and

durability are demanded. For instance, the Ti-TENG was applied as walking step counter by

detecting the motion of the person’s shoe, showing its capability to serve as a self-powered devices.

Therefore, we believe our device can provides a highly promising platform with superior robustness

and durability for applications of self-powered devices to effectively harvest energy from mechanical

movement.

*E-mail :[email protected] (H.-K. Kim), [email protected] (Y.-H. Hwang)

Contact Phone : Tel: +82-55-350-5271 (H.K. Kim), +82-55-350-5274 (Y.-H. Hwang)


P-23

Thermal Conductivity and Interfacial Thermal Resistance

of Gd2Zr2O7 Thin Films

J. H. Kwak , J. G. Kang, and H. S. Yang*

Department of Physics, Pusan National University, Busan 609-785

Gd2Zr2O7, rare-earth zirconates, has been known as a promising candidate for future thermal

barrier coating materials. Gd2Zr2O7 forms in the pyrochlore structure which is similar to the fluorite

structure with 1/8 oxygen missing which results in low thermal conductivity.

Gd2Zr2O7 films are deposited on the Al2O3 substrate as varying film thickness from 105 nm to

663 nm by using RF magnetron sputtering. The structural crystallization, surface roughness, and

thickness of the thin films are characterized with X-ray diffraction, atomic force microscopy, and

scanning electron microscopy, respectively. Thermal conductivity is measured at various temperatures

from 80 K to 298 K by using the 3ω method. Thermal conductivity of Gd2Zr2O7 films exhibit film

thickness dependence and this result is understood with the interfacial thermal resistance between

thin film and substrate.




P-24

Graphene oxide-stimulated myogenic differentiation of C2C12 skeletal

myoblasts

J. H. Lee, M. J. Kim, Y. C. Shin, S. E. Kim, J. S. Kim, J. H. Park and D. -W. Han*

Department of Cogno-Mechatronics Engineering & BK21+ Nano-Integrated

Cogno-Mechatronics Engineering, Pusan National University, Busan 609-735

Graphene, a single layer sheet of sp2-hybridized carbon atoms, has a crystal lattice structure.

Graphene oxide (GO), which is synthesized by oxidization of graphene, has been studied for

biomedical applications, such as drug delivery systems, cell imaging and biosensors, because of its

excellent biocompatibility and physicochemical properties. Many studies have been evaluated the

effect of GO on cell behaviors, including cell attachment, proliferation and differentiation. However,

the effect of GO particles on myoblasts has not been fully revealed yet. In this study, we

investigated the effects of GO particles on C2C12 skeletal myoblasts. The physicochemical

properties of GO particles were characterized by Raman spectroscopy and atomic force microscopy

(AFM). In addition, we evaluated the cytotoxicity of GO particles on C2C12 myoblasts by

measuring the cell viability in growth media containing different concentrations (0 500 ppm) of

GO particles. The viability of myoblasts was determined by using WST-8 assay. Furthermore, we

analysed the myogenic differentiation of myoblasts by immunofluorescence staining for myosin

heavy chains (MHCs), which is a myogenic differentiation marker. It is revealed that the GO did

not exhibit the cytotoxicity at low concentrations ( 30 ppm) and could stimulate the myogenic

differentiation of C2C12 myoblasts. In conclusion, it is suggested that the GO can be used as a

novel biomaterial for skeletal tissue engineering by enhancing cell behaviors.




P-25

Structures and optical studies of the rare-earth-doped Ca5(PO4)3Cl powders

김영경1, 양호순1, 홍경수2

1 부산대학교 물리학과

2 한국기초과학지원연구원 부산센터

Apatite groups constitutes the most of the phosphorus on the Earth. Minerals of the

apatite groups are the main raw materials in the production of phosphorus fertilizers, fodder

and technical phosphates, elementary phosphorus, and phosphor- organic compounds. The

fluorescent features of apatites have several applications, such as detection and identification

of minerals in rocks and ores. The composition of apatite has the general formula

Ca5(PO4)3(F,Cl,OH,O). Since the rare-earth elements substituted for the calcium sites of

apatites become the luminescence centers in a crystallographic environment, the optical features

of apatites are interesting subjects for the phosphor applications.

We prepare Eu3+- and Sm3+-doped calcium chlorapatite [Ca5(PO4)3Cl] powders by using

the solid-state reaction method sintering at 1,100 oC and 1,300 oC, respectively. We

characterize the structures of the synthesized powders by using an X-ray diffractomer, examine

the morphology by using a scanning electron microscope, and the chemical bonding states by

using an X-ray photoelectron spectrometer. We study photophysical properties of the

synthesized apatites by taking absorption, excitation, and emission spectra at room temperature.

We find that apatites with Eu3+ are red-emitting phosphors and have higher efficiency for the

operation with the NUV excitation, while those with Sm3+ are efficient red-orange-emitting

materials.




P-26

Structural phase transition and polarization analysis of non-centrosymmetry

phases in BiOIO3

Nayoung Song and Bog G. Kim*

Department of Physics, Pusan National University, Busan 609-785, South Korea

최근 들어 non-centrosymmetric phase 에 관한 다양한 계산 혹은 실험 결과들이 소개 되고

있다. 우리는 본 발표 논문에서 Bi3+ 와 I5+ 를 포함하고 있는 새로운 물질 (BiOIO3)에서의

non-centrosymmetric phase 에 관한 계산결과를 발표하고자 한다.

우리는 밀도 범함수를 사용하는 VASP을 이용하여, 구조적인 상변화와 자발 분극의 크기

에 관한 계산을 수행하였다. 최근 실험 결과에서 보듯이 본 물질은 상온에서 orthorhombic 구

조를 가지고 있다. 아주 높은 온도에서는 tetragonal 상이 안정된 구조로 생각되어지나 그 에너

지 차이에 의해 낮은 온도에서는 tetragonal 상에 관해서는 관측이 되지 못한다. 우리의 계산결

과로 이러한 에너지에 관한 논의가 보다 정량적으로 접근이 가능하다. 또한 tetragonal 상에서

orthorhombic 상으로의 상전이에 관한 분석을 그룹이론과 모드 분석을 통해 해 봄으로 인해,

산소 사면체의 비틀림이 상전이의 중요한 원인임을 제시하고자 한다. 또한 비선형 광학 상수

에 관한 계산결과도 논의하고자 한다.




P-27

First Principles Study on the Structural Stability between TiO2 Rutile and TiO2

Anatase

K. S. Choi1* and C. H. Park2

1Department of Physics, Pusan National University, Busan 609-7852Research Center for Dielectric and Advanced Matter Physics, Department of Physics

Education, Pusan National University, Busan 609-785

The electronic structure and the structural stability between TiO2 Rutile and TiO2 Anatase was

investigated through the first Principle calculation based on Density Functional Theory. Specially we

focused on the band alignment between two polytypes. The LDA+U method was applied for the

comparison of the electronic structure and the total energy. We tried to understand the structural

rearrangement between Anatase and Rutile with respect of the Ti-3d and O-2p hybridization.




P-28

Microwave Tunable Properties of CPW Phase Shifter Based on Barium

Stannate Titanate Thin Films

H. C. Ryu1* and S. J. Lee2

1Department of Car Mechatronics, Sahmyook University, Seoul 139-742, Korea2Component & Materials Research Laboratory, Electronics and Telecommunications

Research Institute, Daejeon, 305-350, Korea

Barium stannate titanate (Ba(Ti1-x,Snx)O3, denoted as BTS) thin films were deposited on MgO

substrate using pulsed laser deposition. The crystalline structure properties of BTS were investigated

by X-ray diffractometer; the thickness of the films were investigated using a scanning electron

microscope. Tunable dielectric properties of BTS thin films were measured using interdigitated

(IDT) capacitor structure and coplanar waveguide (CPW) phase shifter at room temperature. IDT

capacitor based on an epitaxial BTS film exhibited the large capacitance tunability of 82 % at a

frequency of 100 kHz and applied voltage of 40 V. And the CPW phase shifter showed a large

differential phase shift of 220 ° at 35 GHz and applied voltage of 40 V. These results indicate that

the thin BTS film can be used for the highly efficient microwave tunable devices.




P-29

One-dimensional hematite nanostructures for photoelectrochemical water splitting

Do Hong Kim1,2, Young-Seok Shim1, Moon Cheon Woo1, Koo Tak Hong1, Jong-Myeong

Jeon1, Yeon Hoo Kim1, Ki Chang Kwon1, Jun Min Suh1, Dinsefa Mensur1, Jong-Heun Lee2,

and Ho Won Jang1*

1Department of Materials Science and Engineering, Seoul National University, Seoul

151-744, Korea2Department of Materials Science and Engineering, Korea University, Seoul 136-361,

Korea

Hematite has recently stimulated increasing attention because of their promising applications in

fields such as solar hydrogen generation by water photoelectolysis. For this application, since the

device performance largely depends on the surface-to-volume ratio of the hematite electrodes or

catalysts, tremendous efforts have been devoted to synthesize hematite nanomaterials with large

specific surface areas.

Among them, one-dimensional hematite nanostrucures have attracted great interest owing to the

facile synthesis of them using anodic oxidation. Highly ordered hematite nanostructures are an

effective design strategy for taking advantage of one-dimensional nanostructures such as high

surface-to-volume ratio and novel functionalities of hematite.

Herein, we report facile synthesis of one-dimensional hematite nanostructures with large specific

surface area for water splitting cells. The obtained efficiency is among the highest reported values

for a hematite based photoelectrochemical cell. This enhancement in the photoconversion efficiency

is related to the unique structural properties of the fabricated porous hematite films. The additional

virtue, the simplicity in the synthesis method, would broaden the applications of the porous

hematite nanostructures to various devices including sensors, batteries, and photochromic glasses.




P-30

A New Approach to the Negative Capacitance of Ferroelectric Thin Films

Y. J. Kim1*, Y. H. Park1, Y. H. Lee1, H. J. Kim1, W. Jeon1, T. Moon1, K. D. Kim1,

D. S. Jeong2, H. Yamada3, and C. S. Hwang1

1Department of Materials Science and Engineering and Inter-university Semiconductor

Research Center, College of Engineering, Seoul National University, Seoul 151-744,

Korea. 2Electronic Materials Center, Korea Institute of Science and Technology, Hwarangno

14-gil 5, Seongbuk-gu, 136-791 Seoul, Republic of Korea.3National Institute of Advanced Industrial Science and Technology (AIST) and JST,

PRESTO, Higashi 1-1-1, Tsukuba, Ibaraki 305-8562, Japan.

Enhancement of capacitance by the negative capacitance effect in dielectric/ferroelectric (DE/FE)

stacked film is gaining a greater interest as a feasible solution to solve insufficient charge problems

of miniaturized capacitors and field effect transistors for future semiconductor devices. Since its first

model suggested by Salahuddin and Datta in 2008,[1] showing the strong polarization coupling

between the DE and FE layers, several remarkable experimental proofs on the capacitance boost of

DE layer when FE layer was stacked on top were reported. However, the quantitative theoretical

background of this intriguing effect that has been proposed by the aforementioned authors holds a

self-contradictory problem, and therefore needs an alternative theoretical approach. In addition, the

Landau-Ginzburg-Devonshire type energy function cannot be applied to describe thermodynamical

feature of low dielectric constant DE layers. Therefore, this work suggests a conceptually

straightforward model to describe the energy of DE/FE system which could calculate the

capacitance boost effect quantitatively. The model was applied to all perovskite systems, such as

SrTiO3/BaTiO3, as well as to a system containing conventional DE layer of Al2O3. The model also

calculated the electrical influence of the trapped charge on the DE/FE interface, which was hardly

adopted in the previous model, and the results were compared with the experimental polarization-

voltage curve of amorphous-Al2O3/epitaxial-BaTiO3 layer grown on epitaxial-SrRuO3/DyScO3 single

crystal.

[1] S. Salahuddin, S. Datta, Nano Lett. 8, 405-410 (2008)




P-31

Study on the wake-up phenomenon of ferroelectric Hf0.5Zr0.5O2 thin films by

polarization switching and discharge behavior

H. J. Kim*, M. H. Park, Y. J. Kim, T. Moon, K. D. Kim,

Y. H. Lee, and C. S. Hwang

Department of Material Science & Engineering and Inter-university Semiconductor

Research Center, Seoul National University, Seoul 151-744, Korea

Recently, it was reported that thin HfO2 films can show ferroelectric properties when doped

with various dopants such as Zr, Si, Y, Al, Gd, La and Sr. It is generally accepted that the

ferroelectricity within these materials originate from the formation of non-centrosymmetric Pca21

orthorhombic phase.[1] The feasible ferroelectricity (remanent polarization >20μC/cm2) with

extremely small thickness (<10nm) is considered highly promising for various applications.

Surprisingly, the ferroelectric HfO2 films show wake-up phenomenon with increase of the remanent

polarization up to certain number (~105) of electric field cycles. Zhou et al. reported that such

wake-up phenomena of ferroelectric HfO2 films are induced by redistribution of defects, such as

oxygen vacancies, which exist near top and bottom electrode.[2] However, it is quite difficult to

investigate their microstructure transition during electric field cycling. In this study, the wake-up

phenomenon of ferroelectric Hf0.5Zr0.5O2 thin films is analyzed by pulse switching measurement.

Using these methods, the capacitance of electrode-ferroelectric interface and contact resistance could

be obtained from transient switching current curve. In our result, only interfacial capacitance is 2~3

times increased with arising wake-up phenomenon. It suggests that the non-switching interfacial

layer with low dielectric constant is partly changed into switching layer possibly due to the

redistribution of defects such as oxygen vacancies.

[1] J. Muller, et al., Nano Lett. 12, 4318 (2012)

[2] D. Zhou, et al., Appl. Phys. Lett. 103, 192904 (2013)




P-32

Photoactivity of Nanocrystalline Bismuth Vanadate Photoanodes Prepared by

Anodic Electrodeposition

Migyoung Lee1*, Hoon Kee Park1, Seonyong Lee1, Seokhoon Choi1, Jaeho Choi1,

Byung Suh Han1, Boreum Lee1, Seo Yun Park1, H. W. Jang1

1*Oxide Nanostructures & Nanoelectronics Laboratory, Department of Materials Science

& Engineering, Seoul National University, Seoul, KOREA

Bismuth vanadate (BiVO4) is a promising photoanode material for the oxidation of water, but

this material has disadvantages such as excessive electron-hole recombination, poor charge transport.

So in this study, we improved the property of BiVO4 by controlling various parameters.

Nanocrystalline BiVO4 films were synthesized by simple anodic electrodeposition under mildly

acidic condition. The deposition mechanism involved oxidation of V5+ ions to V6+ ions and

precipitated out with Bi ions to form amorphous BiVO4 films on the FTO. The as-deposited films

were then converted to crystalline BiVO4 (monoclinic structure) with yellow color when annealed in

air at 500℃ for 6h. The as-deposited and annealed films were characterized by UV-vis

spectroscopy, X-ray diffraction, and scanning electron microscopy. And the photoactivity of annealed

films was studied by measuring linear sweep voltammetry in solution of 0.1M KH2PO4 with 0.1M

Na2SO3 at pH 6.6 using 3-electrode system. All BiVO4 films were back-illuminated through the

FTO because back-illumination resulted in much higher photocurrent generation, which is often

observed for photoelectrodes with poor conductivity. We adjusted deposition parameters including

the V/Bi ratio, time, voltage and annealing condition. The BiVO4 photoelectrodes by preparing

under the best condition had result that 0.8mA/cm2 of average photocurrent at 1.23V vs. RHE. We

are going to doping and fabricating heterojunction electrodes to inhance photoactivity of water

oxidation.




P-33

Switchable all oxide capacitor with nm-thick ferroelectric BaTiO3: a direct

evidence for ferroelectric critical thickness

P. Murugavel1,3*, S. R. Lee1,2⧧, Y. J. Shin1,2, Daniel Sando1,2, J.-G. Yoon4

and T. W. Noh1,2

1Centre for Correlated Electron Systems, Institute for Basics Science (IBS), Seoul

151-747, Korea2Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea

3Department of Physics, Indian Institute of Technology Madras, Chennai-600036, India4Department of Physics, University of Suwon, Hwaseong, Gyeonggi-do 445-743, Korea

Scaling properties of materials characteristics down to nanoscale are fetching interest in view of

understanding the fundamental physical properties and its application potential such as magnetic

dead layer and ferroelectric critical thickness. Though the ferroelectric oxides are an important class

of advanced materials due to their wide range of application potentials, such scaling issues with

respect to thickness, which degrade device performance, are not completely settled yet. It has been

believed that depolarization field is critical for polarization degradation at nanoscale [1]. Critical

thickness for ferroelectricity has been studied using theoritical methods: for example, 6 unit cell

(uc) for BaTiO3 (BTO) is predicted [1]. Further theoritical study estimated 3 uc of the critical

thickness for BTO by using frozen-phonon calculations [2]. Experimental studies for ferroelectric

scaling properties, however, have been bounded mostly due to difficulties for obtaining high quality

ultrathin ferroelectric films. In a capacitor structure, the reported critical thickness limit is about 3

uc for PbTiO3 using X-ray scattering technique [3]. In our study, we have succeeded in fabricating

ultra-thin ferroelectric BaTiO3 films down to about 1 nm by employing La0.67Sr0.33MnO3 and SrRuO3

as a top and a bottom electrodes, respectively, using piezoresponse force microscopy (PFM). Further

experimental results such as retention will be presented.

References

[1] J. Junquera and Ph. Ghosez, Nature (London) 422, 506 (2003).

[2] G. Gerra, A.K. Tagantsev, N. Setter, and K. Parlinski, Phys. Rev. Lett. 96, 107603 (2006).

[3] D.D. Fong, G.B. Stephenson, S.K. Streiffer, J. A. Eastman, O. Auciello, P.H. Fuoss, C. Thompson,

Science 304, 1650 (2004).


⧧E-mail : [email protected]



P-34

X-ray radiation effects in P(VDF-TrFE) using atomic force microscopy

Owoong Kwon1, Hyeon Jun Lee2, Hosung Seo1, Hye Jeong Lee2, Ji Young Jo2,

Yunseok Kim1*

1School of Advanced Materials Science and Engineering, Sungkyunkwan University,

Suwon 440-746, Republic of Korea2School of Materials Science and Engineering, Gwanju Institute of Science and

Technology, Oryong-Dong, Buk-Gu, Gwangju 500-712, Republic of Korea

Polyvinylidene fluoride-trifluoroethylene P(VDF-TrFE) copolymer has been used in various

applications such as information storage devices and energy harvesting systems due to flexibility

and low processing temperature, etc. There are several studies of radiation effects on the

P(VDF-TrFE) film. It was reported that new phase can be formed by the x-ray irradiation and,

accordingly, ferroelectric property can be changed after the irradiation. We observed similar behavior

in our P(VDF-TrFE) thin films. To explore the influence of the irradiation on the electrical

properties, piezoresponse force microscopy (PFM) and electrostatic force microscopy (EFM) were

used for measuring switching and surface potential behavior, respectively. The hysteresis loop

opening, measured by PFM, of the pristine region is larger than that of the irradiated region. In

addition, we measured EFM at several different frequencies of 1st and 2nd harmonics to observe

surface and internal electrical properties. These results represent that x-ray irradiation makes some

change on the electrical properties in the P(VDF-TrFE) copolymer by phase transition.




P-35

Reaction Pathway of Steam Methane Reforming

on Ni3M (111) (M = Rh, Ru) Surface: A DFT Study

Hanmi Kim1, Jaichan Lee1*

1School of Advanced Materials Science & Engineering, Sungkyunkwan University, Suwon,

440-746, Republic of Korea

Solid oxide fuel cells (SOFCs) are of great interest, in particular because of their relatively

high fuel flexibility. In addition to anode of the solid oxide fuel cell, nickel has been widely used

as a catalyst for methane dissociation of fueling. In the process, carbon deposition is often

accompanied by the methane dissociation, which causes to deteriorate cell performance of SOFC.

Density functional theory (DFT) was used to investigate the dissociation process of methane on

nickel and doped nickel (111) surfaces. Reaction path of the dissociation to CH3, CH2, CH, C, H

on Ni (111) and Ni3M (111) (M = Rh, Ru) surface was traced by calculating adsorption and

activation energies in each dissociation step. Additionally, the generation mechanism of CO gas was

investigated. The transition states and activation energies were calculated by the nudged elastic band

(NEB) method. Alloying nickel by ruthenium reduces the activation energies of the dissociation into

of CH4, CH3, CH2 and CH while the activation energy of the dissociation of CH is not changed.

The activation energy of the step for CH + O CHO is decreased for ruthenium alloying slab.

This indicates that Ni3Ru is an effective way to enhance the dissociation of methane and reduce

the carbon deposition.


Contact Phone : 031)299-4743


P-36

Frequency dependent electromechanical response for distinguishing different

origins in strain-based atomic force microscopy

Daehee Seol1, Seongjae Park1 and Yunseok Kim1*

1School of Advanced Materials Science and Engineering, Sungkyunkwan University (skku),

Suwon, 440-746, Republic of Korea

Strain-based atomic force microscopy (s-AFM) techniques such as piezoresponse force

microscopy (PFM) and electrochemical strain microscopy (ESM) have been developed for probing

of local electromechanical (EM) response at the nanoscale. However, since origins of EM response

are diverse on the different materials such as ferroelectrics and electrochemical devices, it is

important to investigate their different origins when characteristics of materials is not known.

Recently, Chen et al reported several methods for distinguishing electrochemical response and

piezoresponse1. However, since their approach is based on the harmonics and hysteresis loop

measurements, there is a limitation on its application. In this presentation, we reported frequency

dependent Vac sweep which is a simple method for distinguishing EM response on the

electromechanically active samples. We have chosen Li-ion conductive glass ceramics (LICGC),

composed of ionic and piezoelectric phases, and Pb(Zr,Ti)O3 as model samples. We observed that

EM response caused by ionic motion is increased according to decrease Vac frequency whereas

piezoresponse is not changed. In addition, we observed spatial variation of frequency dependent

ionic and piezoelectric response in the LICGC. There observations show that ionic and piezoelectric

response show different behavior at different frequency regime. These results could provide

additional method to investigate different origins of EM response.

References

[1] Q. N. Chen, Y. Ou, f, Ma and J. Li, Appl. Phys. Lett. 104, 242907 (2014)




P-37

Homoepitaxial single- and poly-crystalline SrTiO3 thin films

Sungmin Woo1, Hoidong Jeong1, Sang A Lee1,2, Hosung Seo3, Morgane Lacotte4, Adrian

David4, Hyun You Kim5, Wilfrid Prellier4, Yunseok Kim3, WooSeokChoi1*

1Department of Physics, Sungkyunkwan University, Suwon, 440-746, Korea2Insitute of Basic Science, Sungkyunkwan University, Suwon, 440-746, Korea


Suwon, 440-746, Korea4Laboratorie CRISMAT, CNRS UMR 6508, ENSICAEN, Normandie Universite, 6 Bd

Marechal Juin, F-14050 Caen Cedex 4, France5Department of Nanomaterials Engineering, Chungnam National University, Daejeon,

305-764, Koreaysics, Pusan National University, Busan 609-785

Studying poly-crystalline transition metal oxides (TMOs) in comparison to the single-crystals,

provide various intriguing physical insight to the materials system. In particular, electronic and ionic

conduction at the grain boundaries, phonon propagation, and various domain properties can be

assessed through an accurate comparison between the two crystal structures. Here we propose an

approach to simultaneously fabricate both single- and poly-crystalline epitaxial TMO thin films on

SrTiO3 substrates. In order to grow TMO thin films epitaxially with atomic precision, an atomically

flat surface of the substrate is a prerequisite. We examined various single- and poly-crystalline

SrTiO3 surfaces, which required different annealing conditions for atomically flat surfaces. By

considering the surface energy of the domains with different crystallographic orientations, we

successfully prepared atomically flat poly-crystalline SrTiO3 surface. We then fabricated

homoepitaxial single- and poly-crystalline SrTiO3 thin films by controlling the elemental vacancies

in the film. The comparison between the crystal structures offers interesting physical aspects

regarding TMO domains and grainboundaries.




P-38

Crystal and electronic structure of homoepitaxial SrTiO3 thin films with

elemental vacancies

Sang A Lee1, Hoidong Jeong1, Sung Min Woo1, Jae-Yeol Hwang2, Seul Ki Roh1,

Jung Seek Hwang1, Sung Wng Kim2,3, and Woo Seok Choi*,1,2

1Department of Physics, Sungkyunkwan University, Suwon, 440-746, Korea2IBS Center for Integrated Nanostructure Physics, Sungkyunkwan University, Suwon

440-746, Republic of Korea3Department of Energy Sciences, Sungkyunkwan University, Suwon 440-746, Korea

Perovskite strontium titanate (SrTiO3, STO) has attracted attention owing to its large dielectric

constant, good insulating property and high chemical stability. It is also one of the most popular

substrates for epitaxial growth of perovskite transition metal oxide thin films and heterostructures. It

is well-known that elemental defects such as oxygen vacancies induce changes in the crystal and

electronic structure of the material. For example, oxygen vacancies induce metallic, and further

more, superconducting state in STO. In this presentation, we have systematically investigated the

formation and the role of elemental vacancies in STO homoepitaxial thin films. We used pulsed

laser epitaxy (PLE) in order to grow homoepitaxial STO thin films under various oxygen partial

pressure from 10-6 to 10-1 Torr to control the amount of elemental defects in the thin films. We

separately identified the role of oxygen and Sr vacancies in the homoepitaxial STO thin films.

While oxygen vacancies were responsible for the metallic behavior of the film, lattice expansion

was mainly due to the Sr vacancies induced with the oxygen vacancies. In addition, while the

oxygen partial pressure and the flow rate of the oxygen in the chamber was critical in determining

the oxygen vacancies in the sample, the shape of the plume (dynamics of the plume) was

responsible for inducing the Sr vacancies.




P-39

Enhanced Photon Absorption of Titanate Nanosheets

Bongwook Chung1, Minoru Osada2 and Jaichan Lee1*


Suwon 440-746, Republic of Korea2International Center for Materials Nanoarchitectonics (MANA), National Institute of

Materials Science (NIMS), Tsukuba 305-0044, Japan

TiO2 has been extensively studied for photocatalyst application. Pure TiO2 has low light

absorption since it has a large band gap, 3.2 eV. To absorb long wavelength light more efficiently,

chemical doping have been used to reduce band gap. However, the reduced band gap decreases the

driving forces of photocatalytic oxidation and reduction reactions, resulting in reduced photocatalytic

efficiency. To keep the high driving forces as well as to absorb long wavelength light, we studied

two dimensional TiO2 nanosheets which has a wider band gap than bulk one due to quantum

confinement effect. The TiO2 nanosheets are codoped by transition metal and halide ions.

GGA-PBE+U scheme was used in this study. We found an intermediate state in the Fe-F or Co-F

codoped TiO2 nanosheets. The intermediate state allows the long wave light absorption through

successive absorptions: from VBM to the intermediate state and from intermediate state to CBM.

This intermediate band enables TiO2 nanosheets to absorb long wavelength light while keeping the

wide band gap. We propose that this intermediate band of codoped nanosheets enhances the

photocatalytic efficiency via the band structure modification.




P-40

Tailoring of Electron-Phonon Coupling in Artificially Designed Superlattice

Minsu Choi1, Taejun Hwang1, Jiwon Seo1, Tran Min Dao1 and Jaichan Lee1*


Suwon, 440-746, Republic of Korea

We design artificial superlattices to tune the degree of distortion of octahedron and investigate

the function of the distortion on the electrical properties. (La0.75Sr0.25VO3)2/(LaVO3)2n with n = 1, 2,

3, 4, and 5 superlattices were grown on stepped LaAlO3 (001) single crystal substrate using pulsed

laser deposition method. The reflection high energy electron diffraction oscillations and atomic force

microscopy images confirm two dimensional layer-by-layer growths in the films. Both DC and AC

electrical properties of (La0.75Sr0.25VO3)2/(LaVO3)2n superlattices were investigated by 4-point probe

method. The results demonstrate that electron-phonon coupling can be tuned by periodicity of

artificial vanadate superlattice. By controlling V-O-V bond angle mismatch at interfaces between

La0.75Sr0.25VO3 with little VO6 octahedron distortion and LaVO3 with larger distortion, we manipulate

the strength of electron-phonon coupling. Our findings suggest a new way to control of their

coupling in a situation that control over the coupling is still lacking despite marvelous advance in

engineering nanostructures.




P-41

Surface sulfurization of laser-ablated WO3 films for solar water splitting

Chulmin Youn, Joonbong Lee, Heejin Lee, Ho Jin Lee and Taekjib Choi*

1Hybrid Materials Research Center and Department of Nanotechnology and Advanced

Materials Engineering, Sejong University, 143-747

Solar water splitting to hydrogen and oxygen over a semiconductor is a promising process of

clean and sustainable energy production. Among metal oxides, WO3 is one of relatively smaller

band gap semiconductors, which is highly attractive for electrochromic, photochromic, and

photocatalytic applications. WO3 is also a active material of photoelectrode for the water splitting,

because of its proper band gap to absorb blue part of visible light and the ultraviolet region in the

solar spectrum. WS2 has received much interest in solar water splitting owing to excellent hydrogen

evolution reaction. In this study, WO3 thin films was prepared on transparent conducting oxide/glass

substrate by pulsed laser deposition. WO3 nanostructures were optimized for improved

photoelectrochemical performance. WS2/WO3 heterostructure have been fabricated by sulfurization

using chemical vapor deposition. X-ray diffration and Raman analysis showed the formation of

WS2. Solar water splitting characteristics were investigated by 3-electrode cell with I-V curve, cyclic

voltammetry and impendence analysis.




P-42

Enhanced Photoelectrochemical Properties of Oxide Semiconductor

Heterostructures

Wooyoung Choi, Chulmin Youn, Joonbong Lee, Heejin Lee, Ho Jin Lee, and Taekjib

Choi*

Hybrid Materials Research Center and Department of Nanotechnology and Advanced

Materials Engineering, Sejong University

TiO2 is a well-known candidate of photoelectrode for photoelectrochemical applications owing

to its low cost and high activity. Especially, TiO2 nanotube based photoelectrodes could also

provide increased surface area for electrochemical reaction. However, the solar energy harvesting of

TiO2 photoelectrodes have been limited to ultraviolet (UV) light. Various strategies, including

surface modification, cocatalysis, and heterostructure have been investigated to enhance

photoelectrochemical performance. In this study, we have utilized the band alignment of

anatase-rutile TiO2 and heterojunctions of BiFeO3 and TiO2. The band alignments offer the driving

force for the improved photoelectrochemical properties because of the significantly enhanced charge

transport. BiFeO3/TiO2 heterostructures showed the enhanced the visible-light absorption and solar

water splitting. The presence of thin ferroelectric BiFeO3 layer greatly contributed to the enhanced

photovoltaic response by promoting carrier separation due to an increase in the internal field

across heterostructure arising from spontaneous polarization. Therefore, our results provide effective

routes for developing highly efficient photoelectrode based on oxide semiconductor heterostructures.




P-43

Non-volatile resistive switching effect of LaAlO3/SrTiO3 heterostructures

Sungmoon Hwang1, Yeonsoo Kim2, Baeho Park2 Taekjib Choi1*

1Hybrid Materials Research Center and Department of Nanotechnology and Advanced

Materials Engineering, Sejong University, Seoul, 143-747, Korea 2Division of Quantum Phase & Devices, Department of Physics, Konkuk University,

Seoul 143-701, Korea

The two-dimenstional electron gas (2DEG) at interface between two band insulators LaAlO3

and SrTiO3 has attracted much interest due to its fascinating properties such as high mobility,

ferromagnetism and superconductivity. We have investigated out-of-plane electrical transport of

LaAlO3(LAO)/Nb:SrTiO3 (0.5 w.t.%) (NSTO) structure.

We have deposited LaAlO3 thin film on Nb doped SrTiO3 substrate with various condition by

pulsed laser deposition. Scanning transmission electron microscopy and high-resolution X-ray

diffraction was carried out for investigation of interfacial and crystallographic structure, respectively.

In addition, we have found non-volatile resistive switching behavior through out-of-plane electrical

measurement, which was affected by thickness of LAO layer and the reduction of NSTO surface.

We will also discuss multi-level resistance states with different applied bias and electrical transport

mechanisms.




P-44

Resistive switching in TiO-SiO composite films after soft breakdown

Tae-Sup Yoo, Chan-Goo Park, and Jong-Gul Yoon*

Department of Physics, University of Suwon, Hwaseong, Gyunggi-do 445-743

여러 비휘발성 메모리 중 MIM (metal-insulator-metal)의 구조를 가진 소자는 산화물과

전극의 특성에 따라 다양한 resistive switching 현상을 보여준다. 하지만 아직까지 이러한

현상에 대한 근본적인 이해와 soft breakdown 등에 대한 여러 부분에서 연구할 것들이 많이

남아있다. 우리는 aerosol-assisted chemical vapor deposition 방법을 이용해 420도에서

Pt/Ti/SiO /Si 기판에 TiO-SiO 혼합 박막을 증착하였으며, 진공 증착기를 이용해 Au 전극을

증착하여 Au/TiO-SiO /Pt 의 구조를 가진 MIM 소자를 만들었다. TiO-SiO의 혼합 비율에

따라 Current - Voltage 특성을 측정하여 전기적 특성을 비교하며, 혼합비율에 따라 달라지는

전기적 특성이 resistive switching 현상에 어떤 변화를 주는지를 확인하고 이러한 변화를

이용해 메모리 정보의 신뢰도와 관련된 on/off 비를 증가시키는데 중점을 두었다. 또한 soft

breakdown을 일으키는 조건을 변화 바꾸면서 resistive switching에 어떤 영향을 주고 이용할 수

있는지 확인해봤다. SiO의 첨가 비율에 따라 on/off 비가 점차 변화하는 것을 확인했으며,

몇몇의 혼합 비율의 박막에서 soft breakdown을 일으키기 위한 전류의 방향에 따라 on/off 비의

차이가 생겼다. 또한 전극의 유무에 따라 soft breakdown 전후에 전기적 특성의 차이도

확인했다. 이것들을 이용해 우리는 on/off 비를 10배 이하에서 약 50배까지 변화시킬 수

있었고 이러한 결과와 원인에 논의해볼 것이다.




P-45

Pt-nanoparticle imbedded ZnO-based thin films for ultra-violet photodetector

Khalkhulin Daniil, Seong-Hoon Kim, Hyuna Im, and Jong-Gul Yoon*

Department of Physics, University of Suwon, Hwaseong, Gyunggi-do 445-743

Metal nanostructures are of great interest for optoelectronic applications because of their

localized-surface-plasmon (LSP) resonance in the presence of external light. In particular, Pt

nanoparticles (NPs) posses a wider tunable LSP energy varying from deep ultraviolet (UV) to

visible region depending on their morphology. The novel properties of the NPs has offered new

opportunities to engineer and improve the performance of optoelectronic devices. In this work, we

investigate the effects of the inclusion of Pt NPs in ZnO-based thin films on its photodetection

performance. ZnO is one of the promising materials for UV photodetectors because of its direct

wide bandgap (3.3 eV), environment friendliness and low cost. We deposit ZnO thin films

embedded with Pt NPs by aerosol-assisted chemical vapor deposition on various substrates. The

current-voltage characteristics of the films under dark and UV illumination conditions are reported.




P-46

Piezoelectric Properties of Bismuth Copper-based Lead-free Ceramics

Achiri Tange, Hee Sung Kim, Chang Won Ahn and Ill Won Kim*

Department of Physics and EHSRC, University of Ulsan, Ulsan 680-749, Korea

Piezoelectric ceramics are widely used in electromechanical systems due to their good

piezoelectric properties. Lead zirconate titanate (PZT) has been dominant in this respect because it

possesses much superior piezoelectric properties as well as a high Curie temperature near its

morphotropic phase boundary (MPB). Recently due to environmental concerns (because of the

toxicity of lead) there is the need to look for alternative lead-free piezoelectric systems with

properties close to or comparable to that of PZT.

Bismuth copper-based lead-free perovskite materials are interesting because of the effect of

copper in inducing more distortion to the perovskite structure at low fields, thereby improving the

ferroelectric and piezoelectric properties. We have synthesized a lead free piezoelectric material

(1-x)Bi0.5(Na0.78K0.22)0.5TiO3-xCu(Bi0.5Ti0.5)O3 (BNKT-BCuT) using a conventional ceramic process and

studied its physical and piezoelectric properties. The addition of small amounts of BCuT was found

to have a small effect on both the shape of the P-E and S-E hysteresis loops as well as

polarization values. Both the remnant polarization Pr and the coercive field Ec were found to

decrease gradually with increasing BCuT content. The strain was significantly increased for x =

0.01 and decreased monotonically with increasing BCuT content with maximum normalized strain

d33* = 500 pm/V at 50 kV/cm. This suggests that this material (for x = 0.01) could be a

promising candidate for actuator applications.




P-47

Electric Field-Induced Strain of Lead-Free Bi0.5Na0.5TiO3-Bi0.5K0.5TiO3 Ceramics

Modified with BaZrO3

T. H. Dinh1, J. K. Kang1, C. H. Lee1, C. D. Park1 Y. H. Hong1 and J. S. Lee1*

1School of Materials Science and Engineering, University of Ulsan 680-749

This study investigated the crystal structure and electric field-induced strain (EFIS) properties of

Bi-rich side of (1-x)[(1-y)Bi0.5Na0.5TiO3 yBi0.5K0.5TiO3]-xBaZrO3(BNT-BKT-BZ)system(x = 0-0.05; y

= 0.14, 0.18, and 0.22). BNT-BKT-BZ ceramics were prepared via conventional method and their

phase structure, microstructure, ferroelectric and EFIS properties were studied. All samples reveal a

relative dense microstructure with pure perovskite structure without any secondary phase. A typical

nonergodic relaxor (NER) behavior was found in (1-y)BNT-yBKT samples with a large remnant

polarization (Pr), large maximum coercive field (Ec), and a typical butterfly shape in the strain

(S-E) curve. With increasing amount of BZ in (1-y)BNT-yBKT system, both Pr and Ec of ceramics

decrease and the P-E loop becomes slimmer close to that of ergodic relaxor (ER) material, that

generally demonstrate a linear P-E loop. The “negative strain” defined as the difference between

zero-field strain and the lowest strain is close to zero and the S-E loop exhibits a drastic deviation

from those of nonergodic relaxor materials. The ternary phase diagram of BNT-BKT-BZ based on

XRD analyses and S-E loop was presented. The largest normalized strain was found to be 640

pm/V at x = 0.3 and y = 0.14, it could be related to the electric field-induced phase transition

between nonergodic relaxor and ergodic relaxor phases under electric fields. It has been also

proposed that the polarization extension from a nonergodic relaxor to an ergodic relaxor phase

under electric fields enhances strain.




P-48

Polar discontinuities and piezoelectric properties of honeycomb lattices

Mohammad Noor-A-Alam and Young-Han Shin*

Department of Physics and EHSRC, University of Ulsan, Ulsan 680 749

Polarity has become an increasingly active research area in the field of oxide surfaces1, where

polar discontinuities drive a metal-insulator transition and the appearance of a two-dimensional

electron gas. Based on first principles calculations, we find that such polar discontinuity in

honeycomb lattices (e.g. graphene, h-BN, and silicene, etc.) is also possible by breaking inversion

symmetry through chemical functionalization2,3. Here we study hydro-fluorinated silicene monolayer

and multilayers. We show that a band gap covering a range from 1.36 eV to 2.15 eV can be

opened in various monolayer configurations. Moreover, piezoelectricity can be engineered into

non-piezoelectric silicene. Our piezoelectric constants are comparable with other known 2D

piezoelectric materials (e.g. hydro-fluorinated graphene/h-BN) and some bulk semiconductors, such as

wurtzite GaN and BN. However, band gap disappears for multilayers because of electronic

reconstruction stemming from uncompensated surfaces charges.

References:

1) C. Noguera and J. Goniakowski, Chem. Rev. 113, 4073 (2013).

2) H. J. Kim, M. N. A. Alam, J. Y. Son, and Y. H. Shin, Chem. Phys. Lett. 603, 62 (2014).

3) M. N. A. Alam, H. J. Kim, and Y. H. Shin, Phys. Chem. Chem. Phys. 16, 6575 (2014).




P-49

Precise measurement of piezoelectric coefficients of PVDF-TrFE films

using a Laser Doppler Vibrometer

Bong Chan Park#, Amir Ullah, Chang Won Ahn and Ill Won Kim*

Department of Physics and Energy Harvest-Storage Research Center,

University of Ulsan, South Korea

The piezoelectric effects in films are being intensively explored for their promising applications

as sensors and actuators in a variety of micro and nano systems. An efficient characterization

technology for the piezoelectric properties of the films, particularly the piezoelectric coefficients, is

becoming more and more essential for both fundamental research and applications. However, the

variation of error among the reported data for piezoelectric films is significantly large amount. The

reason is that no widely accepted standard measurement technique has been popularly used for

films. Some of the measurement methods are not accurate. In this study, we had prepared different

kinds of experimental setup for the determination of the piezoelectric coefficient d33 to improve the

measurement reliability and accuracy and obtained optimization of the experimental conditions using

a Laser Doppler Vibrometer due to its high resolution and advantages of nondestructive

measurement.

The PVDF-TrFE(Poly vinylidene fluoride trifluoroethylene) films were fabricated by sol-gel

processing on Pt/Ti/SiO2/Si substrates and annealing at 140 . The thickness of the films was 2µm.

The films were unclamped with a fixture which was attached to a transition stage on an optical

table. The alternating current driving electrical fields was applied to the PVDF-TrFE piezoelectric

films to stimulate the vibration. A large longitudinal piezoelectric coefficient d33 of PVDF-TrFE film

were obtained 5pm/V at 11kHz without substrate clamping effect. Several key points were discussed

in order to achieve reliable and accurate results.

*E-mail : #[email protected], *[email protected]



P-50

CH3NH3PbI3-xClx 두께 변화에 따른 페로브스카이트 태양전지 효율

Sujung Park, and Shinuk Cho*

Department of Physics and EHSRC, University of ulsan 680-749, South Korea

최근 유기 금속 할로겐화물의 페로브스카이트 구조에 기반을 둔 유-무기 하이브리드 태양

전지가 획기적인 태양전지의 한 기술로써 떠오르고 있다. 페로브스카이트 역구조 태양전지의

간단한 구조와 저온 솔루션 공정 태양전지라는 장점은 저비용으로 고비용의 모폴로지 최적화

필요 없이 소자 제작을 가능하게 한다. 본 연구에서는 CH3NH3PbI3와 CH3NH3PbI3-xClx를 활성

층으로, [6,6]-phenyl-C61- butyricacidmethylester (PCBM) 을 전자 수송 물질이자 정공 차단 물질

로 사용하여 저온 솔루션 공정을 통해 제작 된 페로브스카이트 태양전지에서 페로브스카이트

층과 PCBM 층 계면에서 일어나는 전하 분리를 통해 각 전극으로 전자-정공이 잘 도달하기

위해서는 페로브스카이트 활성 층과 PCBM 전자 수송 층/정공 차단 층의 두께가 소자 효율에

영향을 받으므로 활성 층 두께에 따른 효율 변화를 연구하였다. 활성 층두께에 따른 최적화

조건을 찾음으로써 10.2%의 페로브스카이트 역구조 태양전지 효율을 달성하였다.




P-51

Self-polarization in the a lead-free (K0.5Na0.5)(Mn0.005Nb0.995)O3 ferroelectric thin

films on Nb:SrTiO3 substrate from interfacial strain relaxation

Hae Jin Seog1, Chang Won Ahn1, Song A Chae1, Kwang-Eun Kim2, Chan-Ho Yang2,

Tae Yeong Koo3 and Ill Won Kim1*

1Department of physics and Energy Harvest-Storage Research Center, University of

Ulsan, Ulsan, 680-749, South Korea2Department of Physics, KAIST, Daejeon, 305-701, South Korea

3Pohang Accelerator Laboratory, Pohang, Gyungbuk, 705-784, South Korea

In recent years, lead-free piezoelectric films have received increasing attention for environmental

protection. The (K,Na)NbO3 (KNN)-based material is a promising lead-free candidate for various

actuators, sensors and transducers in the micro-electro-mechanical systems (MEMS) owing to its

high Curie temperature and excellent piezoelectric properties. However, almost systematic work did

not report in the KNN-based thin films so far except for some studies on (001) preferred

orientation. In this study, the (001) preferred-oriented (K0.5Na0.5)(Mn0.005Nb0.995)O3 (KNMN) thin film

grown on Nb:SrTiO3 (Nb:STO) single-crystalline substrate is used to investigate the spontaneous

self-polarization associated with strain relaxation. It is confirmed that the lattice mismatch between

KNMN thin film and Nb:SrTiO3 substrate creates an interfacial strain gradient, there by producing

strong imprint in a P-E hysteresis loop, i.e., shifting toward ordinate with a distorted shape. The

PFM image exhibited the dark contrast overall in the as-grown state, whereas the bright brown

square area was created by an electric poling at a sample bias of +10 V. The downward

self-polarization of the KNMN thin film occurred by strong inhomogeneous compressive strain due

to strain relaxation. The self-polarization provides a useful insight into self-polarization engineering

by control of strain relaxation and flexoelectricity.




P-52

First-principles study of the effect of oxygen vacancies around the 180°

ferroelectric domain walls of tetragonal PbTiO3

Hoe-Cheol Song, and Young-Han Shin*

1Department of Physics and EHSRC, University of Ulsan, Ulsan 680-749, Korea

People have extensively studied the dynamics of ferroelectric materials to apply them to

nonvolatile memory devices. One of the critical issues in ferroelectric random access memory is the

fatigue effect, which results from the presence of defect like oxygen vacancy. Many cycles of

polarization switching increase the density of oxygen vacancy around ferroelectric domain walls, and

it makes the ferroelectric energy barrier higher to slow down the switching rate. In this research,

we examine the domain dynamics around the 180° ferroelectric domain walls of tetragonal PbTiO3

with and without the oxygen vacancy by using the first-principles calculations. We estimate the

energy barriers of several possible reaction paths with the nudged elastic band method. Compared

to the oxygen vacancy far away from domain walls, the oxygen vacancy around ferroelectric

domain walls tends to be thermodynamically stable with lower energy barriers. As the density of

oxygen vacancy increases around the domain wall, the energy barrier of domain wall motion

increases. The energy barrier of the oxygen vacancy migration in domain wall system decreases

when it moves with the domain wall, however, the computed value is 0.08 eV higher than vacancy

free case. From this research, we conclude that the oxygen vacancy tends to stay with the domain

wall and make the energy barrier higher, consequently, cause the fatigue effect (reduce the speed of

switching process).




P-53

Piezoelectric P(VDF-TrFE) Thin Film Power Generators on Paper Substrates

for Wearable Device Applications

Sung Sik Won1,2, Nicholas Mostovych2, Angus I. Kingon2, Ill Won Kim1* and

Seung-Hyun Kim2#

1Dept. of Physics and Energy Harvest-Storage Research Center, Univ. of Ulsan, Korea2School of Engineering, Brown University, Providenece, RI02912, USA

The objective of this research is to develop a new class of flexible energy harvesting devices

for self-powered wearable electronic systems. A critical issue of all piezoelectric wearable devices is

the need to reduce the size and the weight so that devices with increased functionality can be

incorporated into a wider range of physiological locations and applications. Use of polymeric

piezoelectric thin films on paper substrates, however, is potentially beneficial for the fabrication of

large-area and complicated-shaped devices with low cost, light weight and size scaling.

In this study, we introduce a new approach for enlarging the sensing capacity and the power

generation of the devices using piezoelectric P(VDF-TrFE) co-polymer thin films coupled with

cellulose paper substrates. Our results demonstrate that with stringent precursor and process control,

excellent ferroelectric and piezoelectric properties of P(VDF-TrFE) thin films can be achieved. In

addition, our suggested flexible paper-based structure shows a high degree of freedom with no

shape limitation and has a good formability, enabling us to cut or shape the devices by using

simple tools such as stamping, punching, or cutting without complex MEMS-based process. Our

P(VDF-TrFE) thin film-based paper power generators are demonstrated to improve power output and

efficiency due to high flexibility, high mechanical compliance, low resonance frequency, and good

piezoelectric response.

*E-mail : #[email protected], *[email protected]



P-54

Low Temperature Sintering of 0.74(Bi0.5Na0.5TiO3)-0.26SrTiO3 Ceramics by

Adding CuO as a Sintering Aid

D. H. Lee1, J. K. Kang1, T. H. Hinh1 and J. S. Lee1*

1School of Materials Science and Engineering, University of Ulsan 680-749

This study investigated the effect of CuO additive on the sintering beahvior and electric

field-induced strain properties of Bi1/2Na1/2TiO3-SrTiO3 (BNT-ST) ceramics. Ceramic specimens were

prepared using a conventional solid-state reaction route. In case of BNT-ST specimen without CuO

aid required sintering temperature (Ts) as high as 1175 oC for sufficient densification, while the Ts

of BNT-ST added with 1 mol% CuO ceramic was lowered down to 1100oC. The unipolar strain of

1 mol% CuO addded specimen reached 550 pm/V under an electric field of 4 kV/mm, which is

promising for low cost multilayer actuator applications.




P-55

Properties of [0.98{Bi1/2(Na0.78K0.22)1/2TiO3}-0.02LaFeO3]-Bi1/2(Na0.82K0.18)1/2TiO3

Lead-Free Piezoceramic Composites

C. H. Hong1*, H. S. Han2, J. S. Lee3, W. Jo1

1School of Materials and Engineering, Ulsan Institute of Science and Technology, Ulsan

689-7982Institute of Materials Science, Technische Universität Darmstadt, Darmstadt 64287

3School of Materials and Engineering, University of Ulsan, Ulsan 680-749

To overcome the challenges that large stains in a Bi-based lead-free piezoelectrics are only

achieved at relatively high electric fields, relaxor (RE)-ferroelectric (FE) ceramic composite concept

was recently proposed as a viable solution1, 2. Here, the relaxor presents the large strain responses,

and the ferroelectric causes the electric field applied to ferroelectric to be intensified locally so that

the driving electric field required for activating large strains can be virtually reduced.

(Bi1/2(Na0.82K0.18)1/2TiO3 (BNKT), 0.98(Bi1/2(Na0.78K0.22)1/2TiO3-0.02LaFeO3 (BNKT2LF) ceramic

powders were synthesized using a conventional solid-state reaction method, and then BNKT2LF was

mixed with BNKT with the composition of 0, 0.1, 0.2, 0.3, 0,5 and 1 mole fractions.

As the BNKT content was increased from 0 to 1 the normalized electric-field-induced strain

(Smax/Emax)was seen to be activated at lower field levels. The best strain property of 500pm/V

was achieved in BNKT2LF-10BNKT at as low as 3kV/mm. The results shows that FE in RE

expedites phase transition of RE to FE at low field, which demonstrates the encouraging potential

of lead-free piezoceramic composites for actuator applications which have low voltage sources such

as mobile devices.




P-56

Investigation of the local work function distribution and resistance change of

VO2/Al2O3 and VO2/TiO2 thin films spanning the metal-insulator transition

Ahrum Sohn1, TeruoKanki2, Hyun-TakKim3,4, and Dong-WookKim1,*

1Department of Physics, Ewha Womans University, Seoul 120-7502The Institute of Scientific and Industrial Research, Osaka University, Osaka, Japan

565-0871 3Metal-Insulator Transition Lab., ETRI, Daejeon 305-700

4School of Advanced Device Technology, University of Science and Technology (UST),

Daejeon 305-350

For several decades, numerous researches have investigated intriguing physical properties of

VO2. VO2 undergoes the metal-insulator transition (MIT) and monoclinic-to-tetragonal structural

phase transition (SPT) near the room temperature (~340K). During MIT, the magnitude of the

resistivity change is over 4 orders. In this study, we comparatively studied MIT behaviors of two

kinds of VO2 thin films, which were grown on Al2O3 and TiO2 single crystal substrates. In

particular, we observed their spatial distribution of work function spanning MIT using KPFM

(Kelvin probe force microscopy). The film on the Al2O3 substrate consisted of tiny grains (grain

size: tens of nm) due to large lattice mismatch. On the other hand, the film on the TiO2 substrate

had much larger grains and the MIT temperature is ~300K due to negligibly small lattice

mismatch. KPFM enabled us to reveal the local electronic structure of the sample via its work

function. The work function of the both samples decreased as increasing the sample temperature

above the MIT temperature. In this presentation, we will discuss the influences of the grain size on

the MIT behaviors of VO2 thin films.




P-57

Structural and electrical properties of epitaxial PbTiO3 thin films on conducting

LaNiO3 grown by laser ablation

H. J. Jin, S. H. Oh, and W. Jo*

Department of Physics, Ewha Womans University, Seoul, 120-750

Ferroelectric PbTiO3 is one of the interesting ferroelectrics showing large spontaneous

polarization of 75 μC/cm2 at room temperature. In this paper, epitaxial PbTiO3 thin films were

deposited on SrTiO3(001) and LaAlO3(001) by laser ablation under various deposition conditions.

With an optimized condition, highly c-axis oriented PbTiO3 thin films were achieved and phase

formation and lattice variation of the thin films were investigated by x-ray diffraction patterns. In

addition, conducting LaNiO3 were used as a bottom electrode to examine electrical properties of

PbTiO3 thin films. To verify local ferroelectric properties and domain transport behaviors of the thin

films, piezoelectric force microscopy and conducting atomic force microscopy was used. From the

microscopic studies, we explored switching characteristics of the c-/a-domains and their charge

conduction over the domain walls which reveals the domain dynamics of ferroelectric materials.




P-58

Dielectric properties of PIN-PMN-PT Films Prepared by Aerosol-Deposition

Method

S. B. Kang1, Y. M. Kong2, J. H. Ryu3, L. Wang4 and D. Y. Jeong1*

1School of Materials Sci. & Eng., Inha University, Incheon, 402-7512Department of Materials Sci. & Eng., University of Ulsan, Ulsan, 680-749

3Functional Ceramics Group, Korea Institute of Materials Science, Changwon, 641 8314Electronic Materials Research Laboratory, Xi’an Jiaotong University, Xi’an 710049,

People’s Republic of China

PIN-PMN-PT(Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3) is one of the relaxor-PT based

ferroelectric materials.The relaxor-PT based materials revealed low dielectric loss, high dielectric

permittivity and electromechanical properties. As the rhombohedral PIN-PMN-PT has broadened

temperature usage range (rhombohedral tetragonal phase transition temperature, TR-T>120oC), the

ternary PIN-PMN-PT could be applied for capacitors in the electronics, transducers, MEMS and etc.

In this research, We deposited the PIN-PMN-PT thick films by aerosol-deposition (AD) method.

The films deposited by AD method revealed nano-sized grain and dense film structure. The AD

method can fabricate film through the collision of fine ceramic powder particles onto the substrate

at room temperature. The (sub-)micrometer sized particles are crushed nano size, and have strong

adhesion between films and substrate. The films revealed the slim polarization - electric field

hysteresis loop due to the nano-size effect. Through the post annealing process, grain size and

crystallinity can be controlled, resulting in the improvement of the electrical properties of the AD

films. We compared dielectric and ferroelectric properties of the aerosol deposited films. The

ferroelectric properties, the dielectric constant by a change of the frequency were measured using an

impedance analyzer. The polarization - electric field (P-E) hysteresis loops were examined using a

standard ferroelectric test system.




P-59

A 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 based pyroelectric generator and temperature

sensor

Young Joon Ko, Byung Kil Yun, and Jong Hoon Jung

Department of Physics, Inha University, Incheon 402-751

We report the extremely high pyroelectric power generation of a relaxor ferroelectric

0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3(PMN-PT)single crystal. The pyroelectric current and voltage of

PMN-PT depend on the electric poling voltage, temperature variation rate, and measurement

temperature. Near the structural transition temperatures of the rhombohedral-tetragonal transition

(~380K) and tetragonal-cubic transition (~410K), the temperature induced change of electric

polarization results in the sharp enhancement of pyroelectric power. Near the tetragonal-cubic

transition temperature, i.e. the Curie temperature, we have observed pyroelectric current of ~100 nA

and voltage of ~11 V. Near room temperature, we have observed pyroelectric current of ~1.4 nA

and voltage of ~0.2 V from the touch of a human finger. These results imply that the relaxor

ferroelectric PMN-PT should be quite useful for pyroelectric energy harvesting and temperature

sensing applications.




P-60

Room-temperature hydrogen gas sensing properties of Co3O4/Nb2O5 composite

nanoparticles

S. H. Kim, S. H. Park, H. J. Kheel and C. M. Lee*

Department of Materials Science and Engineering, Inha University, Yonghyun-dong,

Nam-gu, Incheon 402-751, Republic of Korea

Co3O4/Nb2O5 composite nanoparticles were synthesized using a sol-gel process and their H2 gas

sensing properties were examined. The multiple networked composite nanoparticle sensor showed

responses of 137-516 % at 0.01-1.0% of H2 at room temperature. The responses of the composite

nanoparticle sensor to 0.01-1.0% of H2 were stronger than those of the pure Nb2O5 nanoparticle

sensors by 1.1-2.2 times. The former sensor showed faster response than the latter sensor. The

composite nanoparticle sensor showed selectivity for H2 gas over CO, acetone, methane and NH3

gases. The paper discusses the underlying mechanism for the enhanced response, sensing speed and

selectivity of the composite nanoparticle sensor for H2 gas.




P-61

Fabrication, structure and gas sensing properties of Pt- functionalized ZnS

nanowires

S. Park, S. Kim, G. Sun and C. Lee1*

1Department of Materials Science and Enginnering, Inha University, Incheon 402-751

Pt-functionalized ZnS nanowires were synthesized on Au-deposited (0001) sapphire substrates by

thermal evaporation of ZnS powders followed by wet Pt coating and annealing. The NO2 gas

sensing properties of multiple-networked Pt-functionalized ZnS nanowire sensors were examined.

Scanning electron microscopy showed the nanowires with diameters ranging from 20 nm to 80 nm.

The diameters of the Pt nanoparticles on the surfaces of the ZnS nanowires ranged from 20-50 nm.

Transmission electron microscopy and X-ray diffraction showed that the nanowires were

wurtzite-structured ZnS single crystals. The Pt-functionalized ZnS nanowire sensors showed enhanced

sensing performance to NO2 gas at 150oC compared to pristine ZnS nanowire sensors. Pristine and

Pt-functionalized ZnS nanowire sensors showed responses of 140 211% and 207 - 488%,

respectively, to 1-5 ppm NO2 at 150°C, which are comparable to or better than those of many

oxide semiconductor sensors. This results support a possibility of practical use of Pt-functionalized

ZnS nanowires as a sensor for NO2 gas detection. Inaddition, the underlying mechanism of the

enhanced sensing properties of the Pt-functionalized ZnS nanowires is discussed.




P-62

Electric polarization and diode-like conduction in hydrothermally grown

BiFeO3 thin films

T. K. Lee and J. H. Jung

Department of Physics, Inha University, Incheon 402-751

We report the successful synthesis of high-quality BiFeO3 thin films on a SrRuO3/SrTiO3

substrate using hydrothermal methods, and their structural, ferroelectric, and electrical properties.

Using alow precursor concentration, we obtained compressively strained BiFeO3 thin films

(thickness: 60 nm) with smooth surface (roughness: 4.2 nm). The ferroelectric polarization of the

BFO thin films was parallel with respect to the normal to the substrate and changed direction by

180o under the application of electric field. The current flowed unidirectionally; such rectifying

behavior was attributed to Schottky barrier modulation by oxygen vacancies and ferroelectric

polarization. Our results provide an important step in the applications of hydrothermally grown

BiFeO3 thin films like a large-area and low-cost photovoltaic device.

*E-mail : [email protected], [email protected]



P-63

Electrical Properties of Polyvinyldene-fluoride-ZnO Modified CNT

Nanocomposite Film by Spray coating

J. H. Lim1, J. k. Lee1, H. J. Kim1, I. J. No2, Y. M. Kong3, and D. Y. Jeong1*

1School of Materials Science and Engineering, Inha University, Incheon 402-751, Korea2School of Electrical Engineering, Inha University, Incheon 402-751, Korea

3Department of Materials Sci. & Eng. University of Ulsan, Ulsan, 680-749, Korea

The β -phase Polyvinyldene fluoride (PVDF), a typical polymer ferroelectrics, has been widely

studied due to its high dielectric constant, superior piezoelectric and electrocaloric effect compared

to other polymers. The PVDF has four different crystal structures: α-phase; β-phase; γ-phase; δ

-phase. Because of the significant piezoelectric property in the β-phase PVDF film, the β-phase of

PVDF film is very important at the application of actuator. Therefore the researches to make the β

-phase have been carried out. The β-phase PVDF film was usually fabricated by stretching along

the length direction or poling process. It was known that PVDF can be made to poled state by and

during spray coating process without appling the electric field.

In this work, the PVDF films were fabricated by spray-coating method. A ZnO modified

Carbon nanotube (CNT) was included as a additive into the PVDF solution to change electrical

properties. For comparison, the PVDF and CNT nanocomposite PVDF films were also fabricated

by spray-coating process.




P-64

Synthesis of Homogeneous Nanocrystalline LiFePO4 by Two Step Polyol

Process and Their Performance

S. J. Kim, J. J. Song, J. H. Gim, B. J. Paul, J. G. Jo, W. G. Park, Y. P. Oh,

S. K. Nam, and J. K. Kim*

Department of Materials Science and Engineering, Chonnam National University

(email:[email protected])

Mono-dispersed and densely packed, LiFePO4 cathodes with high rate performance versus

lithium were synthesized using a two-step polyol process. The particle-size distribution and packing

density of LiFePO4 nanoparticles were fine-tuned via separation of the nucleation and particle

growth processes in the polyol medium by varying reaction time and temperature. Precisely, the

LiFePO4 samples were synthesized by heating the reaction mixtures at 200 C for various reaction

times (0, 1, 3 and 6 h) to facilitate nucleation and thereafter the solution temperature was raised

and maintained at 320 C to facilitate the crystal growth process. XRD studies confirmed the

formation of olivine phase in all the samples. The FE-SEM, FE-TEM and particle-size distribution

studies illustrate that the particle-size of olivine nanocrystals may be tuned to approximately 200

nm by controlling the aging time at 200 C or in other words separating the nucleation and crystal

growth process. The olivine cathodes synthesized by maintaining 3 6 h aging time demonstrate

improved discharge capacities and cycle performances in comparison to those of the remaining

samples. In particular, the 6 h olivine cathode registered average discharge capacities of 130, 87

and 64 mAh/g at 5 C, 10 C and 15.7 C current rates respectively.




P-65

Nanostructure carbon coated LiFePO4 by a scalable polyol combustion

synthetic strategy

J. H. Gim1, V. Mathew1, S. H. Kim1, D. Y. Kim1, Y. E. Kim1, D. C. Ahn2,

W. B. Im1, Y. K. Paik3 and J. Kim1,*

1Department of Materials Science and Engineering, Chonnam National University,

Gwangju 500-757

2Beamline Research Division, Pohang Accelerator Laboratory, Pohang 790-8343Daegu Center, Korea Basic Science Institute, Daegu 702-701


In the present study, carbon-coated lithium iron phosphate (LiFePO4/C) is prepared directly by

a polyol assisted pyro-synthesis performed under reaction times of a few seconds in open-air

conditions. The polyol process is generally represented by the reaction of metallic precursors in a

polyol solvent maintained near or at its boiling point. Here, the polyol solvent, tetraethylene glycol

(TTEG), acts as a low-cost fuel to facilitate combustion and the released exothermic energy

promotes the nucleation and growth processes of the olivine nanoparticles. In addition, phosphoric

acid (used as the phosphorous source) acts as a catalyst to accelerate polyol carbonization. The

structure analysis of the as-prepared LiFePO4/C using X-ray and neutron diffraction and 7Li NMR

studies suggested the efficacy of the rapid technique to produce highly crystalline phase-pure olivine

nanocrystals. The electron microscopy and particle-size distribution studies revealed that the average

particle diameters lie below 100 nm and confirmed the presence of a surface carbon layer of 2-3

nm thickness. The thermal and elemental studies indicated that the carbon content in the sample

was approximately 5 %. The prepared LiFePO4/C cathode delivered capacities of 162 mAh/g at 0.1

C-rate with impressive capacity retention for extended cycling. The polyol-assisted pyro-synthesis,

which evades the use of external energy sources, is not only a straightforward, simple and timely

approach but also offers opportunities for large-scale LiFePO4/C production.




P-66

Impedance Spectroscopy on Multiferroic Bi0.5K0.5TiO3-BiFeO3

Su-Hyun Moon, Ji-Hoon Kim, Eui-Chol Shin, John Gerard Fisher and Jong-Sook Lee*


500-757, Korea

For the electrical characterization of ferroelectric materials, dielectric constants and loss tangent

values are presented as a function of temperature at fixed frequencies. Strong frequency dispersion

observed in many complex perovskites could not be clearly explained and thus the Curie

temperature becomes poorly defined. A Voigt model for the grain boundary and electrode

polarization for the finite resistance high temperature behavior. Model analysis employs constant

phase elements with arbitrarily adjustable frequency dispersion instead of the ideal capacitor models

and resistors. The approach is problematic in characterization of the dielectric properties since the

capacitances are poorly defined. Often, a Maxwell model for the dielectric relaxation is also

employed for the same AC data with an inherent inconsistency. The AC behavior of much studied

BiFeO3-related multiferroic complex oxides shows these issues with a further complication of the

coupling between the electrical and magnetic properties. Electrical modeling where two dieletric

polarization effects and DC resistance are connected in parallel is found to competently describe the

AC behavior over the wide temperature ranges, where the dispersive response is described by a

Cole-Davidson dielectric function in parallel to the ideal capacitance element. Two capacitance

effects appear to correspond to the dielectric behavior of Bi0.5K0.5TiO3 and BiFeO3, respectively,

suggesting the application of the additivity and universality of the ion polarizabilities well-known

for the silicate minerals.




P-67

Understanding electrochemical reaction of orthorhombic NCO using in-situ

X-ray Diffraction for sodium ion batteries

J. J. Song, J. H. Gim, S. J. Kim, J. G. Jo, S. H. Park, P. T. Duong, J. H. Yang, J.

Lee, and J. K. Kim,*

Department of Materials Science and Engineering, Chonnam National University


In this work, almost pure NaxCoO2 (x = 0.71) sample has been prepared via a solid-state

route. The stoichiometric composition has been estimated by ICP-AES analysis and the Rietveld

refinement performed on the respective XRD pattern led to an orthorhombic structure in the Cmcm

space group with a = 2.83218(3)Å, b = 4.89983(4)Å, c = 10.92334(14)Å. The insertion/deinsertion

of sodium into the well-crystallized particles leads to capacities as high as 70.4 mAhg-1 with an

initial Coulombic efficiency of 90%, and excellent capacity retention of almost ~100% after the

90th cycle between a 2.0~3.5 V voltage window for a 0.08 C-rate. The insertion ratio (x) varied

between 0.592 and 0.673 during the deinsertion/insertion process within NaxCoO2. The voltage

profile shows numerous voltage steps being mainly associated to the slight ordering of the Na ions

within the layers. By coupling the electrochemical process with an in-situ X-ray diffraction

experiment, the c-axis and a-axis peak positions such as (002), (004) and (100) are shifted with the

accompanying deintercalation/intercalation of sodium, suggesting that the extracted sodium has been

reversibly occupied with a small variation in sodium composition ranges due to peculiar

Na+/vacancy ordering.




P-68

In-depth Electrical characterization of Dye-Sensitized Solar Cells by Impedance

Spectroscopy Method

Dang-Thanh Nguyen1, Seok Jae Kim3, Eui-Chol Shin1, Soon-Hyung Kang2, Eun-Mi Han3

and Jong-Sook Lee1*

1School of Materials Science and Engineering, Chonnam National University, Gwangju

500-757, Korea2Department of Chemistry Education, Chonnam National University, Gwangju 500-757,

Korea3School of Applied Chemical Engineering, Chonnam National University, Gwangju

500-757, Korea

In spite of the worldwide extensive research efforts for the developments of dye-sensitized solar

cells in-depth electrical characterization using impedance spectroscopy appears to be limited to a

very few research groups. In this work, we characterized standard dye-sensitized solar cells (DSSCs)

constituted of a nanostructured TiO2 semiconductor on a transparent conducting oxide (TCO), a

photoactive dye material (N719 dye), and Pt counter electrode by impedance spectroscopy method

as well as IMVS/IMPS. In IMVS/IMPS the kinetic parameters including the recombination lifetime

and transport coefficients and diffusion length of the DSSCs are estimated using light-modulated

approaches by AC measurements at different light intensities at open-circuit/short-circuit condition,

respectively. The light sources are 530nm and 627nm. The impedance is measured at different

potential values of current-voltage curves including open-circuit/short-circuit condition in dark and

under illumination at different wavelength and intensity. The general impedance model reported by

Bisquert group has been successfully applied. The kinetic parameters from impedance analysis are

compared with those from IMVS/IMPS. The difference in the cell performance of many laboratory

prepared cells will be in-depth understood.




P-69

Moving boundary diffusion mechanism in non-monotonic hydration/dehydration

AC relaxation in protonic conducting perovskites

Dong-Chun Cho, Gye-Rok Kim, Eui-Chol Shin and Jong-Sook Lee*


500-757, Korea

Recently, the mechanism generally applied to all protonic ceramic conductors exhibiting

non-monotonic conductivity relaxations has been revealed. Similarly activated faster hydrogenation

and slower oxygenation process can be explained by the moving boundary diffusion mechanism

previously evidenced by in-situ optical spectroscopy where the hydrogenation kinetics is limited by

the hydration front. The conventional DC conductivity method provides only the integral

conductivity value of the sample with the non-trivial diffusion processes. The large number of

complex impedance data at different frequencies could provide more information on the situation

inside the materials or devices. Therefore AC method was employed for non-monotonic conductivity

relaxation phenomena in protonic ceramic conductors in perovskite structure. AC measurements were

performed over the frequency range from 10MHz to 10Hz using a disk sample of 5mol%

Yb-doped SrCeO3 (SCYb) and 15mol% Y-doped BaCeO3 (BCY) upon hydration/dehydration at

700°C, 650°C, and 600°C. The frequency sweep requires less than 1 min, which is sufficiently

short to monitor the relaxation proceeding over hours. High temperature spectra, however, are

strongly affected by the stray impedance at high frequencies. Modeling including the stray effects is

thus essential for the parametric analysis. Different AC characteristics of protonically conducting

perovskites will be compared for the model development.




P-70

Polyol-mediated solvothermal synthesis and improved electrochemical

performance of novel K-doped Co3O4 as negative electrode for secondary

lithium-ion batteries

J. G. Jo, Z. Xiu, M. H. Alfaruqi, V. T. Trang, S. G. Lee, and J. K. Kim*

Department of Materials Science and Engineering, Chonnam National University, 300

Young-bong dong, Bukgu, Gwangju 500-757, Korea


The exploration of 3d transition-metal oxides (MO, M = Fe, Co, Ni, Cu, etc.) as negative

electrodes for lithium ion batteries has received great attention recently. These oxides are attractive

alternatives to graphite and they can deliver high reversible capacities. Co3O4 is considered as a

promising alternative anode material for LIBs due to its high theoretical capacity (890mAhg-1). It

can store more than eight lithium ions per formula unit during charge/discharge. However, there are

some factors limit the performance of Co3O4 such as its poor electrical conductivity and large

volume expansion/contraction as well as severe particle aggregation associated with the Li+-insertion

and extraction process, which eventually lead to electrode pulverization and the loss of inter-particle

connectivity. This results in a large irreversible capacity loss and poor cycling stability. It is well

known that the particle size, morphology, and structure of electrode materials play important roles

in determining the electrochemical performance. Several methods have been developed the prepare

Co3O4 and overcome these problems, including the use of carbon based nano-composites and

increasing the specific surface area by preparing nanoparticles with various morphologies and

dimensions. However, to maintain and superior rate capability of the Co3O4 electrode material still

remain challenging issues. In the present work. a novel approach to improve the electrochemical

performance of the Co3O4 nanostructure by potassium ion (K+) doping is reported.

Nanostructure K+-doped Co3O4 was prepared via polyol-mediated solvothermal synthesis.

Electrochemical tests demonstrate that the K+-doped Co3O4 could exhibit high charge/discharge

capacity, long cyclability and high rate capability without noticeable capacity fading. This strategy

features a facile procedure with a novel dopant for realizing the large-scale production of Co3O4

nanoparticles with improved electrochemical performance.




P-71

졸 -겔 방법 및 다공성 알루미나 멤브레인을 이용하여 제작된

Pb(Zr0.52Ti0.48)O3나노튜브 어레이의 압전 특성 연구

김병훈, 양선아, 강신욱, 부상돈*

전북대학교 물리학과, 전주 561-756

대표적인 강유전체 물질인 Pb(Zr,Ti)O3는 높은 압전 특성 (d33=190pC/N)을 가지고 있기 때

문에 널리 사용되고 있다. 최근 강유전체의 나노구조물은 에너지 하베스트, 압전 변환기, 액추

애이터 등과 같은 많은 응용분야에서 매우 유망하다. 특히 나노막대, 나노선, 나노튜브와 같은

1차원의 나노구조물이 주목을 받고 있는데, 이는 전도성 기판위에 균일하게 잘 정렬되어 분포

되어 있는 경우 큰 활동 표면적을 가져 고출력밀도에 활용하기 적절하기 때문이다. 1차원 나

노구조물 중에서도 나노튜브는 속이 빈 구조와 높은 종횡비에서의 안정성 때문에 나노막대나

나노선보다 높은 잠재력을 가진다. 따라서 전도성 기판 위에 균일하게 잘 정렬되어있는 나노

튜브 제작 연구와 압전 특성 연구가 필요하다. 본 연구에서는 졸-겔 방법과 다공성 알루미나

멤브레인을 주형틀로 이용하여 다결정 Pb(Zr0.52Ti0.48)O3(PZT)나노튜브 어레이를 제작하였으며,

그들의 압전 특성을 piezoresponse force microscopy (PFM)을 이용하여 관찰 하였다. PZT 나노

튜브는 Pt/Si 기판 위에 준비된 PAM 위에 PZT 졸-겔 용액을 도포한 후 스핀코팅과 500 oC에

서 700 oC의 다양한 온도에서의 열처리 과정을 거쳐 제작되었다. 그 후 주형틀을 선택적으로

식각함으로써 기판위에 수직적으로 서있는 PZT 나노튜브 어레이를 얻을 수 있었다. 제작된

나노튜브의 평균 직경, 높이, 벽두께는 각각 320 nm, 1000 nm, 그리고 60 nm로 관찰되었으며,

550 oC의 열처리 온도 이상에서 페로브스카이트 구조를 가진 나노튜브가 형성되는 것을 확인

하였다. PFM phase 이미지 분석을 통하여 본래 나노튜브가 가지는 수직방향의 도메인을 관찰

하였으며, 나노튜브의 분극 방향이 외부 전기장에 의해 스위칭 되는 것을 관찰 할 수 있었다.

또한, 열처리 온도에 따른 나노튜브의 압전 특성을 분석한 결과 650 oC에서 열처리한 나노튜

브가 가장 높은 압전 특성을 보이는 것을 관찰할 수 있었다.




P-72

CaBi4Ti4O15세라믹스의 전기적 특성에 감마선 조사가 미치는 영향

전도현, 최기쁨, 조삼연, 부상돈*

전북대학교 물리학과, 전주 561-756

강유전체 물질은 강유전 특성과 압전 특성으로 인해 압전 센서나 비휘발성 메모리 등 많

은 분야에서 널리 이용되고 있으며, 특히 PZT 같은 높은 강유전 특성과 압전 특성을 보이는

물질들이 많이 사용되고 있다. 그러나 최근 우주 항공 산업의 발달과 함께 우주 같은 극한 환

경에서 사용하기 위한 물질에 대한 연구가 활발히 진행됨에 따라, PZT 같은 강유전체 물질은

상전이 온도가 낮은 물질들은 고온에서 활용도가 제한되므로 극한환경에 적합하지 않기 때문

에 상전이 온도가 높은 강유전체 물질에 대한 연구가 필요하다. 강유전체 물질 중CaBi4Ti4O15

세라믹스는 높은 상전이 온도와 낮은 유전상수, 낮은 열화특성, 낮은 온도계수, 그리고 높은

품질계수를 가지기 때문에 우주나 원자력 발전소 같은 극한 환경에서 사용하기 위한 압전 소

자용 물질로 높은 가능성을 보이지만, 아직 방사선 조사에 의한 특성 변화에 대한 연구는 진

행되어 있지 않다. 감마선 조사에 의한 물질의 특성변화 연구는 주로 total ionization dose [1],

displacement damage [2], 그리고 single event effect [3] 세가지 모델을 적용하여 진행되고 있다.

따라서 본 연구에서는 감마선을 조사하여 총선량에 따른 CaBi4Ti4O15세라믹스의 특성 변화를

위의 세가지 모델로 분석하였다.

CaBi4Ti4O15세라믹스는 고상 반응법으로 제작하였으며, 이 시료에 감마선을 조사하여 유전

특성, 압전 특성, 그리고 강유전 특성의 변화를 측정하였다. 준비된 시료는 XRD 분석을 통해

CaBi4Ti4O15단일구조를 확인 하였으며, 100 kHz에서 유전상수 값이 151 그리고 유전손실 값이

0.001로 그리고 상전이 온도는 790 oC로 측정되었다. 이 시료에 0 1 MGy까지 다양한 총선

량으로 감마선을 조사하여 그에 따른 특성 변화를 관찰하였고, 그 결과를 통해서 CaBi4Ti4O15

세라믹스에 감마선 조사가 미치는 영향에 대해 위에서 제시한 3가지 모델 중 가장 적합한 모

델을 제시하고자 한다.

[1] D. Neamen, W. Shedd, and B. Buchanan, Nuclear Science, IEEE Transactions on 21, 211 (1974)

[2] M. Burton, J. Phys. Chem. 51, 611 (1947)

[3] Binder, D., E. C. Smith, and A. B. Holman. Nuclear Science, IEEE Transactions on 22 2675 (1975)




P-73

Carbon-nanotube-encapsuled Ferroelectrics Nanocrystals for Energy Harvesting

by Mechanical Movements

J. K. Han1, D. H. Jeon1, S. Y. Cho1, S. W. Kang1, S. A Yang1, K. Y. Choi2, E. J.

Ra3, J. S. Lim3, and S. D. Bu1*

1Department of Physics, Chonbuk National University, Jeonju 561-7562Department of Physics and Astronomy, Seoul National University, Seoul 151-747

3Thin Film Materials Research Group, Division of Advanced Materials, Korea Research

Institute of Chemical Technology, Daejeon 305-600

Nanogenerators that harvest energy from mechanical vibration are an attractive area of

nanotechnology fields. Recently, composite-type nanogenerator consisting of piezoelectric

nanostructures and multi-walled carbon nanotubes (MWCNTs) is one of the excellent candidates for

the future energy harvesting because of a great electrical and mechanical properties of MWCNTs.

Researches are focused on obtaining highest output power and understanding the role of the

MWCNTs in the composite-type nanogenerators. However, the role of the MWCNTs is not fully

understood because most composite-type nanogenerators are made by mixing MWCNTs and

piezoelectrics in the polymer matrix. The interconnected piezoelectrics on MWCNTs provides not

only key information to understand a systematic role of MWCNTs in nanogenerator property but

also effective transfers the stress occurred to the MWCNT.

We report a successful growth of Pb(Zrx,Ti1-x)O3 (PZT) nanoparticles (NPs) interconnected with

MWCNTs (PZT NPs-CNT) through injection method of sol-gel solution into a filter for squeezing

them and annealing for crystallizing them. High resolution transmission electron microscope analysis

of PZT NPs-CNT reveals that the PZT NPs have a diameter of 20 30 nm and are polycrystalline

with a tetragonal structure. In order to form the flexible thin film, the PZT NPs-CNT was

dispersed in polydimethylsiloxane as a matrix and spin-coated until 200 μm in thickness. By

periodic bending or tapping movements, the open-circuit voltage and short-circuit current of the

PZT NPs-CNT reaches about 3 V and 30 nA, respectively. In order to confirm that the signal

comes from the pieozoelectricity, we measured polarity property by a reverse connection in the

circuit and compared the output voltage with and without poling process. We will discuss the role

of the MWCNTs by measuring the output powers of PZT NPs-CNT.




P-74

The use of (NH4)2WS4 precursor as hole extraction layer in organic

photovoltaic cells

Quyet Van Le, Thang Phan Nguyen, Soo Young Kim*

School of Chemical Engineering and Materials Science

Chung-Ang University 221, Heukseok-dong, Dongjak-gu, Seoul 156-756, Republic of

Korea

This study reports a facile method to fabricate the hole extraction layer (HEL) for organic

photovoltaic cells (OPVs) by thermally annealed (NH4)2WS4 precursor in air condition. The thermal

decomposition of (NH4)2WS4 was systematically study using thermal gravimetric analysis, ultra-violet

photoelectron spectroscopy (UPS), x-ray photoelectron spectroscopy, atomic force microscopy, and

transmittance spectra. The UPS data shows that the work function of HEL based (NH4)2WS4 (250 oC) is 5.05 eV, indicating the good alignment energy between ITO and the active layer based poly

(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester. Therefore, the use of HEL based

(NH4)2WS4 precursor improves the power conversion efficiency (PCE) of OPVs from 1.51 % (OPV

based bare ITO) to 3.14 %, which is comparable to that of device based poly

(3,4-ethylenedioxythiophene):poly(styrene-sulfonate)(PEDOT:PSS) (PCE = 3.23%). In addition,

PEDOT:PSS was inserted between (NH4)2WS4 (250 oC) and active layer, the PCE increase up to

3.41 %, demonstrating that HEL based (NH4)2WS4 precursor is a potential candidate for hole

transfer layer in electronic device.

Acknowledgement

This research was supported by the Mid-Career Research Program (2014R1A2A1A11051098)

through the National Research Foundation of Korea (NRF), which is funded by the Ministry of

Education, Science, and Technology.




P-75

Facile route for the synthesis of MoS2andWS2nanodots

Thang Phan Nguyen, Kyoung Soon Choi, and Soo Young Kim*

School of Chemical Engineering and Materials Science, Chung-Ang University 22,

Heukseok-dong, Dongjak-gu, Seoul 156-756, Republic of Korea

Liquid phase sonication method was adopted to fabricate single layer of molybdenum disulfide

(MoS2) and tungsten disulfide (WS2) by using dodecylbenzenesulfonate 0.1 wt% in de-ionize water

solution. MoS2 and WS2 nanosheets are easily broken by heating the ethylene glycol solvent,

which made MoS2 and WS2 nanosheets to nano dots without employing high pressure or other

complicated conditions. To characterize synthesized MoS2 and WS2, UV-vis absorption, Raman

spectra, x-ray photoemission spectra, and photoluminescence spectra are measured. Peaks of excited

states were shown in UV-absorption spectra in MoS2 nanosheet. Two MoS2 peaks shifted from 693

nm (1.79 eV) and 645 nm (1.92 eV) to 671 nm ( 1.85 eV) and 610 nm (2.03 eV) after heating

treatment, confirming the reduction of size. Exciton peaks of WS2 also changed from 640 nm (1.94

eV) to 624 nm (1.99 eV) when size was reduced to nano sheets. Especially, only one peak

appeared at 296 nm for MoS2 and 322 nm for WS2 after nano sheets were changed to nano dots.

Atomic force microscope image showed that the thickness of single layer MoS2 is 0.65 nm and

that of WS2 is 0.7 nm. Photoluminescence spectra showed that the highest intensity peaks of MoS2

and WS2 are located at 500 nm and 445 nm. These results indicate that MoS2 and WS2 nano

dots could be employed as enhancers or markers in optical devices, bio-image, bio-sensor, and so

on.

Acknowledgement

This research was supported by the Mid-Career Research Program (2014R1A2A1A11051098) through

the National Research Foundation of Korea (NRF), which is funded by the Ministry of Education,

Science, and Technology.




P-76

Piezoelectric and Electrical Properties of Li-doped (Bi0.5Na0.5)TiO3-PVDF

Composite for Energy Harvesting

Joong-Hyeon Ahn and Jung-Hyuk Koh*

School of Electrical and Electronics Engineering, Chung-Ang University, Seoul, 156-756,

Korea

Recently, one of interesting candidates of lead free piezoelectric materials for energy harvesting

is Bismuth sodium titanate(abbreviated to BNT) because of the strong ferroelectric properties.

However, piezoelectric ceramic materials have commonly brittleness, poor fatigue resistance. Polymer

composites have been paid attention owing to their unusual physical properties. For these reasons,

ceramic-polymer composite has been considered to be an alternative for energy harvesting using

piezoelectric materials. To improve the piezoelectric and fatigue resistance properties of BNT

ceramics, BNT based solid solutions have been developed and extensively studied. On the contrary

to common polymers, Polyvinylidene fluoride(abbreviated to PVDF) have piezoelectric, dielectric and

good mechanical properties. The sintering temperature of BNT ceramics is very high

temperature(about 1180 °C) but melting point of PVDF is very low temperature(about 170 °C). To

overcome these problems, lithium as low sintering agent was added into BNT PVDF composite.

In this study, Li doped BNT PVDF composite for energy harvesting was manufactured with

various BNT PVDF ratios (PVDF= 0-20 wt.%). The crystalline properties of BNT PVDF were

investigated by X-ray diffraction (XRD) analysis. The microstructure were observed using field

emission scanning electron microscopy (FE-SEM). In addition, piezoelectric constant, dielectric

constant, mechanical quality factor, electromechanical coupling factor will be discussed.




P-77

Enhanced Piezoelectric and Dielectric Properties of Na0.5K0.5NbO3-CaCu3Ti4O12

Lead-Free Composite

Jae-Hoon Ji and Jung-Hyuk Koh*

School of Electrical and Electronics Engineering, Chung-Ang University, Seoul, 156-756,

Korea

Lead zirconate titanate-based (PZT-based) ceramics have been intensively employed functional

electronic devices applications such as sensors, actuators and transducers due to their excellent

piezoelectric properties. However, the use of lead-based ceramics can contaminate the environment

and deteriorate human health. Owing to these concerns, there have been many attempts to replace

lead-based piezoelectric ceramics with lead-free ceramics. (Na0.5K0.5)NbO3 (NKN) has been

considered candidate for lead-free ceramics due to outstanding piezoelectric properties and Curie

temperature of about 420 °C. However, dense NKN ceramics are difficult to be obtained due to the

volatilization of K-ion and Na-ion at high sintering temperature. To complement this drawback of

NKN ceramics, other materials such as BaTiO3, CaTiO3 and CuO have been added into NKN

ceramics to form solid solution. Therefore, NKN based ceramics can increase densification and

present relatively superior piezoelectric properties. Also, CaCu3Ti4O12 (CCTO) with perovskite-like

compound has high dielectric constant as 12,000 at 1 kHz at room temperature. Thus, NKN-CCTO

can improve densification and dielectric properties. In this study, dielectric and piezoelectric

properties of (1-x)(Na0.5K0.5)NbO3 xCaCu3Ti4O12 (x=0, 0.05, 0.10, 0.15, 0.20) ceramics will be

investigated by conventional mixed oxide method and sintering process. The crystalline structure of

NKN CCTO were measured by X-ray diffraction (XRD) analysis. The microstructure were

examined by scanning electron microscopy (SEM). In addition, piezoelectric coefficient, d33, electro

mechanical coupling factor, kp, mechanical quality factor, Qm, dielectric constant, εr, will be

discussed.




P-78

Temperature Dependent Ferroelectric and Field-Induced Strain Response of

Nb-doped BNBT-SZ Lead-free Piezoelectric Ceramics

Adnan Maqbool,1 Ali Hussain,1 Jamil Ur Rahman,1 Rizwan Ahmed Malik,1 Tae Kwon

Song,1 Won-Jeong Kim,2 and Myong-Ho Kim1*,

1School of Advanced Materials Engineering, Changwon National University, Gyeongnam

641-773, Republic of Korea2Department of Physics, Changwon National University, Gyeongnam 641-773, Republic of

Korea

Lead-free piezoelectric ceramics, (Bi0.5Na0.5)0.935Ba0.065Ti(1 x)NbxO3 0.01SrZO3(BNBTNb100x

SZ, with x = 0 1) were synthesized and its crystal structure, dielectric properties, electric

field-induced strain (EFIS), and polarization response was systematically investigated. X-ray

diffraction analysis revealed that all compositions had a pure perovskite structure with tetragonal

symmetry. The depolarization temperature (Td) shifted toward lower temperature sand the dielectric

curves became more diffuse within creased Nb-doping, producing a significant disruption of the

long-range ferroelectric order. A giant EFIS of 0.33% was achieved at an optimized composition of

Nb1.0 (BNBTNb1.0 SZ), corresponding to a normalized strain (Smax/Emax) of 825 pm/V at a low

applied field of 4 kV/mm. Furthermore, the temperature dependence of polarization and

field-induced strain showed a stable response up to 100°C. These results suggest that BNBTNb SZ

ceramics are promising candidate materials for lead-free actuator applications.

Keywords: lead-free, dielectric, relaxor behavior, incipient piezoelectrics, Electric field-induced strain




P-79

Compositional-induced structural and non-ergodic to ergodic relaxor transition

in lead-free Ta-doped Bi0.5(Na0.84K0.16)0.5TiO3 SrTiO3 ceramics

Rizwan Ahmed Malik1, Ali Hussain1, Arif Zaman2, Tae Kwon Song1,

Won-Jeong Kim3 and Myong-Ho Kim1,*

1School of Advanced Materials Engineering, Changwon National University, Gyeongnam

641-773, Republic of Korea2Department of Physics, Abdul Wali Khan University, Mardan, KPK, Pakistan

3Department of Physics, Changwon National University, Gyeongnam 641-773, Republic of

Korea

The effect of Ta substitution on the crystal structure, electromechanical, dielectric, and

piezoelectric properties of BNKTT ST ([0.96Bi0.5(Na0.84K0.16)0.5Ti1-xTaxO3] 0.04SrTiO3 where x =

0.00 0.030) ceramics has been investigated. X-ray diffraction patterns revealed that Ta doping

resulted in a transition from coexistence of rhombohedral and tetragonal phases to a pseudocubic

phase. Both the dielectric constant and depolarization temperature decreased with an increase in

Ta-content. The piezoelectric and ferroelectric responses of the BNKT ST ceramics was

significantly decreased by the addition of Ta content. However, the destabilization of the

piezoelectric and ferroelectric properties is accompanied by significant enhancements in the bipolar

and unipolar strains. A large electric field-induced strain (S = 0.38%) and a corresponding

normalized strain (Smax/Emax = 633 pm/V) were observed under 6 kV/mm when 2% Ta was

substituted on Ti sites. This significant strain enhancement at x = 0.020 composition may be

attributed to both the compositional-induced structural phase transition and a non-structural non

ergodic to ergodic relaxor phase transition.

Keywords: Lead-free, piezoelectricity, Ferroelectricity, Phase transitions, Electrical properties




P-80

새로운 비납계 BiFeO3-BaTiO3 압전 재료의 물성 평가

D. J. Kim1, M. H. Lee1, J. S. Park1, M.-H. Kim1,

S. S. Kim2, D. Do3, H. Y. Lee4, and T. K. Song1*

1School of Materials Science and Engineering, Changwon National University, Changwon

641-7732Department of Physics, Changwon National University, Changwon 641-773

3Department of Advanced Mat. Eng., Keimyung Univ., Daegu 704-701

4Ceracomp Co., Ltd. Cheonan, 330-816

Bi를 기반하는 물질 BiMeO3 (Me = Fe, Cr, Co)들은 높은 상전이 온도를 가진다고 알려

져 있으며, 특히 BiFeO3 의 경우, 상전이 온도가 830 oC 정도로 높지만 높은 누설 전류로 인해

낮은 강유전성을 가진다. BaTiO3 의 경우, 대표적인 비납계 압전 및 강유전성 재료이나 낮은

상전이 온도로 인해 응용에 제한이 된다. 최근에 BiFeO3 BaTiO3 (BF-BT) 고용체 형성하여 압

전 및 강유전 특성을 보고하면서, 새로운 비납계 압전 재료로서의 가능성을 제시하였다.

현재 비납계 압전 재료의 개발에서 대체로 고상반응법을 이용하여 세라믹 제조 방법이 활

용되고 있으나 실제 응용을 위해서는 후막공정의 개발이 필요하다. 이 후막공정에서 BF-BT계

는 두 가지 정도의 장점을 갖는다. 우선 낮은 소결온도를 갖기 때문에 싼 가격의 내부 전극을

활용할 수 있는 가능성이 높다. 더불어 소결공정이 빠르고 에너지 소비가 적을 수 있다.

테이프 캐스팅 방법을 이용한 BF-BT 세라믹스를 소결 시간에 따른 압전 및 강유전 특성

을 평가하였다. XRD에서는 불순물 상은 형성되지 않았으며, 소결 시간이 증가함에 따라, 낟알

의 크기도 점차 증가함을 알 수 있었다. 조성 분석 결과, 조성 변화가 거의 없는 것을 알 수

있으며, 최적의 소결 시간에서 높은 압전(d33= 189 pC/N) 및 강유전 특성(Pr= 20 μC/cm2 , Ec =

22 kV/cm) 을 관찰하였다. 더불어 BF-BT 박막 제조 및 물성 평가에 대한 연구 결과를 소개한

다.




P-81

Structural, electrical and multiferroic properties of chemical solution deposited

Aurivillius Bi7Fe3Ti3-xNbxO21 thin films

C. M. Raghavan, J. W. Kim, J. Y. Choi, M. J. Lee and S. S. Kim*

Department of Physics, Changwon National University, Changwon, Gyeongnam 641-773

The effects of Nb5+-ion doping on the structural, electrical and multiferroic properties of six

layered Aurivillius Bi7Fe3Ti3O21 thin film are investigated. The Bi7Fe3Ti3-xNbxO21 (x=0 and 0.06)

thin films were prepared on Pt(111)/Ti/SiO2/Si(100) substrates by using a chemical solution

deposition method. Significant improvements were observed in the electrical, dielectric and

multiferroic properties when the Nb5+-ion incorporated into the Ti-site of the Bi7Fe3Ti3O21 thin film.

From electrical study, the Bi7Fe3Ti2.94Nb0.06O21 thin film exhibited low leakage current density of

5.11×10-6A/cm2 at 100 kV/cm, it was about one order of magnitude lower than that of the

Bi7Fe3Ti3O21 thin film. From the ferroelectric study, the Bi7Fe3Ti2.94Nb0.06O21 thin film showed large

remnant polarization (2Pr) of 20.52 μC/cm2 at an applied electric field of 630 kV/cm, while the

measured 2Pr value for the Bi7Fe3Ti3O21 thin film was 3.5 μC/cm2 at an applied electric field of

318 kV/cm. Furthermore, well saturated magnetic hysteresis loop with enhanced magnetization was

observed for the Bi7Fe3Ti2.94Nb0.06O21 thin film.




P-82

Study on the new type of piezoelectric actuator utilizing smooth impact drive

mechanism

M. H. Park1, H. H. Jeong2, S. S. Jeong3 and T. G. Park3*

1Defense Agency for Technology and Quality, Changwon 642-180,

2SAMJEON CO., LTD, Joil-Ri, Samdong-Myeon, Ulju-Gun, Ulsan 1313-3, 3Department of Electrical engineering, Changwon National University, Changwon 641-773

In this paper, the linear piezoelectric actuator utilizing smooth impact drive mechanism(SIDM)

was proposed. It is easy to fabricate actuator because of the simple structure of two bi-morph type

cantilevers without any rotators or sliders. The piezoelectric ceramics, called as legs, were composed

of two rectangular ceramics which were attached on the surfaces of the elastic bodies. FEA

simulation(Ansys) was used to optimize the actuator in order to increase its speed and force. When

rectangular voltages which have basically different ratio of positive and negative signals at

resonance frequency were applied, the piezoelectric actuator was moved by a stick-slip driving

mechanism. The actuator was driven by two successive motions of actuator legs, slow forward

movement and rapid backward movement. The output characteristics of the prototype actuator based

on the analysis data was measured.




P-83

Ferroelectric properties of (1-x)BiFeO3-xBaTiO3 solid-solution thin films

J. S. Park1, M. H. Lee1, S. W. Kim2, D. J. Kim1,

S. J. Han2, S. Kumar3, M-H. Kim1, W-J. Kim2, and T. K. Song1*

1School of Materials Science and Eng., Changwon Nat’l Univ., Gyeongnam 641-773,

Korea2Department of Physics, Changwon Nat’l Univ., Gyeongnam 641-773, Korea

3Institute of Basic Sciences, Changwon Nat’l Univ., Gyeongnam 641-773, Korea

Thin films of lead-free ferroelectric material (1-x)BiFeO3-xBaTiO3 (BF-BTx) (x=0.3, 0.33, and

0.4) were deposited on a Pt(111)/Ti/SiO2/Si(100) substrates by pulsed laser deposition. The films are

deposited at various deposition temperature (550oC-580oC) by maintaining the PLD chamber at an

oxygen partial pressure of 30 mTorr. The BF-BT films were exhibited single-phase perovskite

structure by X-ray diffraction analysis. Deposited at 560oC the BF-BT films. electrical proreties

were shown the good ferroelectric, and low leakage current properties. The BF-BT33 flim was

exhibited remnant polarization 2Pr of about 32 µC/cm2 and coercive field 2Ec of 400

kV/cm. The leakage current at high applied fields was also effectively reduced and leading to

improved ferroelectric properties.




P-84

Na0.5Bi0.5TiO3-BaZrO3 textured ceramics prepared by reactive templated grain

growth method

Ali Hussaina, Jamil Ur Rahmana, Adnan Maqboola, Rizwan Ahmed Malika,

Tae-Kwon Songa, Won-Jeong Kimb, and Myong-Ho Kima*

aSchool of Advanced Materials Engineering, Changwon National University, Gyeongnam

641-773, Republic of Korea bDepartment of Physics, Changwon National University, Gyeongnam 641-773, Republic of

Korea

In this work 0.94Na0.5Bi0.5TiO3-0.06BaZrO3 (NBT-BZ) ceramics were prepared by reactive

templated grain growth(RTGG) method using 15wt.% NBT template. The as synthesized NBT-BZ

textured ceramics were sintered at 1150 oC for different soaking time (2-15h) and their crystal

structure, microstructure, dielectric, ferroelectric and field-induced strain properties were investigated

and compared. Results show that al ltextured NBT-BZ ceramics have(h00) preferred orientation,

which increase with increase in the sintering soaking time. No significant change in the

depolarization temperature was observed in NBT-BZ textured ceramics with change in the sintered

time. However, the field induced strain response increased by 20% when the sintering time was

increase from 2h to 15h.

Keywords: NBT-BZ ceramics; textured ceramics; grain growth


Contact Phone : +82-55-213-3711, Fax: +82-55-262-6486


P-85

New high Curie temperature lead-free piezoceramics

in BiFeO3-BaTiO3 solid solution

이명환1, 김다정1, 박진수1, 김명호1, 송태권1†, 김상욱2, 김원정2, 김상수2, 장기완2

도달현3 , 정일경4

1창원대학교 신소재융합공학과, 창원 641-7732창원대학교 물리학과, 창원 641-773

3계명대학교 재료공학과, 대구 704-7014부산대학교 유전체물성연구소, 부산 609-735

Recently, (1-x)BiFeO3-xBaTiO3 (BF-BT) lead-free piezoelectric systems have potential to be

applied at a high operation temperature due to their high Tc. BF (rhombohedral phase) and BT

(tetragonal phase) solid solutions were observed in the complete compositional range with

rhombohedral (x = 0.00-0.33), pseudo-cubic (x = 0.33-0.92), and tetragonal (x = 0.92-1.00)

perovskite crystal structures.

In this study, (1-x)BiFeO3-xBaTiO3 (x = 0.20 to 0.5) bulk ceramic system was prepared via a

typical solid-state reaction process. The crystal phase, phase transition, microstructure, dielectric,

ferroelectric, and piezoelectric properties as functions of composition were investigated. Detailed

structural and electrical properties of BF BT ceramic will be presented concern with piezoelectric

application.




P-86

Study on the output characteristics of the lambda type ultrasonic motor

depending on the polarization direction of the piezoelectric ceramic

S. K. Cheon1, S. S. Jeong1, Y. W. Ha1, B. H. Lee1, H. I. Jun2, T. G. Park1*

1Department of Electrical Engineering, Changwon National University, Changwon

641-7732Mattron corp, Changwon 630-724

In this paper, the ultrasonic motor which can replace existing ultrasonic motors for driving

camera zoom lens was proposed and experimented. The piezoelectric ceramics was composed of

two rectangular ceramics which was attached on upper surfaces of the elastic bodies as in figure.

The both polarization directions were directed to the outward directions. When two AC voltages

which have basically 90 degree phase difference were applied to the two ceramics, elliptical

displacements of the stator tips were obtained. FEA simulation(ATILA) was used to analyze

elliptical displacement characteristics of the friction tips depending on the polarization direction and

the phase change of applied voltage. The output characteristics of the prototype motor based on the

analysis data was measured.

Stator structure of the proposed ultrasonic motor




P-87

Structure and electrical properties of rare-earth substituted K0.5Bi4.5Ti4O15 thin

films prepared by chemical solution deposition

J. Y. Choi, J. W. Kim, C. M. Raghavan, M. J. Lee and S. S. Kim*

Department of Physics, Changwon National University, Changwon, Gyeongnam 641-773

Ferroelectric thin films have been investigated for decades as nonvolatile ferroelectric random

access memories due to its potentially excellent properties of lower power requirements, faster

access speed and nonvolatility. Recently bismuth layer-structured ferroelectric (BLSF) thin films

have caused extensive attention as promising materials for the nonvolatile ferroelectric random

access memories due to their fatigue-free performance with Pt electrodes. K0.5Bi4.5Ti4O15 (KBTi) is

one of the important BLSFs. However, there were a few reports on the undoped and doped KBTi

thin film form. In this study, effects of Dy3+ and Gd3+-ion doping on the structural, electrical and

ferroelectric properties of the KBTi thin film were investigated. Pure KBTi and rare-earth(Dy3+ and

Gd3+)-doped KBTi thin films were prepared on Pt(111)/Ti/SiO2/Si(100) substrates by using a

chemical solution deposition method. The electrical properties of the thin films were investigated by

P-E hysteresis loops and leakage current conduction behavior measurements.




P-88

Optical ad electrical properties of band-gap controlled

Ge doped ZnO1-xSx thin films

S. J. Han1, S. W. Kim1, M. H. Lee2, J. S. Park2, D. J. Kim2, D. Do3, M. H. Kim2,

T. K. Song2, and W. J. Kim1*

1Department of Physics, Changwon National University, Gyeongnam, 641-773, Korea.2School of Nano & Advanced Materials Engineering, Changwon National University,

Gyeongnam, 641-773, Korea.3Department of Advanced Material Engineering, Keimyung University, Daegu 704-701,

Republic of Korea.

Even though ZnO and ZnS, as II-VI semiconductors, share similarities in chemically and

structurally, both binary compounds do not form a solid solution in the entire compositional range

of S and O due to solubility limits of S in ZnO and O in ZnS in equilibrium states. In order to

fabricate the ZnO1-xSx thin films with 0<x<1, films were intentionally deposited in non-equilibrium

state by a pulsed laser deposition method while controlling oxygen pressures. The formation of the

intermediate structures between ZnO and ZnS were confirmed by an X-ray diffraction study. The

lattice constant changes continuously from ZnO to ZnS as increased S contents. Optical properties,

including energy band gap, and electrical properties were investigated. However, resistivity of

ZnO1-xSx thin films were too large to measure by Hall measurement method. Ge has been doped in

ZnO1-xSx thin film to increase electrical conductivity to study electrical properties of these films.

Details of structural, chemical, optical and electrical properties of Ge doped ZnO1-xSx thin films will

be discussed in the presentation.




P-89

Metal-insulator transition in NdNiO3 by hydrogen doping

C. D Oh1*, S. Y. Heo2, H. M. Jang1,2 and J. W Son1

1Department of Materials Science and Engineering, Pohang University of Science and

Technology, Pohang 790-7842Division of Advanced Materials Science, Pohang University of Science and Technology,

Pohang 790-784

The rare-earth nickelate is perovskite oxide which is sensitive to the orbital occupancy of

electrons. The corner sharing NiO6 octahedra experience charge disproportionation in order to

stabilize the t2g6eg

1 electrons leading Ni4+t2g6eg

0 and Ni2+t2g6eg

2 configuration. Recently, hydrogen is

reversibly intercalated in SmNiO3 leading band gap modulation and giant resistance switching. The

electron configuration of hydrogen doped SmNiO3 is modified from Ni3+t2g6eg

1 to Ni2+t2g6eg

2 and it

suppresses charge disproportionation of NiO6 octahedra. It opens up new directions to explore

emerging electronic devices with nickelate systems.

Here we report a giant resistance change in NdNiO3 epitaxial thin films by hydrogen doping.

We prepared 25 nm-thick NdNiO3 thin film by pulsed laser deposition (PLD). Pt top electrode is

utilized as hydrogen dissociating catalyst. Clear metal-to-insulator transition was observed by color

change in hydrogen-treated NdNiO3 thin films. Electrical characteristic shows the giant change of

resistance. X-ray diffraction (XRD) and atomic force microscopy (AFM) data indicate that the

perovskite structure is maintained during hydrogenation accompanying unit cell expansion. We

demonstrated the resistance change is related to doping concentration of hydrogen and lattice strain.




P-90

Hydrogen-bonding effects in organohalide-perovskite-based solar cells:

first-principles study

June Ho Lee1* and Hyun Myung Jang1,2

1Department of Materials Science and Engineering, Pohang University of Science and

Technology (POSTECH), Pohang 790-784, Republic of Korea2Division of Advanced Materials Science, Pohang University of Science and Technology

(POSTECH), Pohang 790-784, Republic of Korea

During the past two years, there have been rapid advances in solar-energy harvesting research

based on organic-inorganic hybrid perovskite absorbers (e.g., CH3NH3PbI3). The efficiency of this

type of solar cells is, in general, substantially higher than conventional dye-sensitized solar cells

(DSSC). However, these hybrid-perovskite-based solar cells are not fully optimized owing to the

lack of our in-depth understanding. In particular, the role of the organic-cation moiety (CH3NH3)+ is

not known because of their disordered nature of the (configurational) orientation in a perovskite unit

cell.

In order to identify the functional role of the organic-cation moiety in CH3NH3PbI3, we have

carried out first-principles density-functional theory (DFT) calculations focused on the possible

hydrogen-bonding interaction between the iodide (I) anion and the hydrogen (H) ions coordinated to

the nitrogen atom. In the present study, we have systematically investigated the structural change in

response to the variation in the orientation of organic functional groups in a given perovskite unit

cell. To simplify the combination of many possible orientations, we classify each case into

“ferroelectric (FE)” and “antiferroelectric (AFE)" configurations along x, y and z directions.

According to our detailed DFT calculations, the hydrogen bonding between I and H ions plays a

major role in controlling the degree of the tilting as well as the distortion of the PbI6 octahedron

unit in a perovskite unit cell.




P-91

Modulated Spin Structure responsible for the Magnetic-Field-Induced

Polarization Switching in Multiferroic TbMn2O5

Jung-Hoon Lee1, Seungwoo Song1 and Hyun Myung Jang1,2*

1Division of Advanced Materials Science(AMS) and Department of Materials Science and

Engineering, Pohang University of Science and Technology(POSTECH), Pohang 790-7842Department of Physics, Pohang University of Science and Technology(POSTECH),

Pohang 790-784

Orthorhombic TbMn2O5 (o-TMO) is a well-known multiferroic manganite with its remarkable

property of the polarization switching at 3 K under a bias magnetic (H) field along the a-axis of

Pb21m. To theoretically account for this outstanding observation, we have proposed a modulated

spin structure under the saturated bias H-field by considering the relative strength of the three

relevant exchange parameters in o-TMO. The proposed modulated structure based on

density-functional theory (DFT) calculations is described in terms of the spin-angle between the

neighbouring Mn4+-Mn3+ spin moments on the a-b plane. We have shown that the computed DFT

polarization plotted as a function of satisfactorily accounts for the observed H-field-induced

polarization switching. We have further theoretically shown that the square of the critical

field-strength (Hc) needed for the polarization switching is inversely proportional to the degree of

the extrinsic magnetoelectric coupling. The computed partial charge density demonstrates that the

H-field-induced polarization switching also accompanies with the switching in the sign of the excess

valence-electron density.




P-92

Rapid Thermal Heating Effects on the Zn0.85Mg0.15O:Ga Thin Films

Byeong-Eog Jun1*, Sunwoo Kim2, Sangwoo Kim2, Seongmin Lee2 , Jimin Koo2, and

Jong Rim Lee1

1Department of Physics and Earth Science, Korea Science Academy of KAIST, Busan

614-1002Korea Science Academy of KAIST, Busan 614-100

Gallium doped Zn0.85Mg0.15O (ZMO:Ga) thin films were studied for the fabrications of the

transparent homo double layers of the conductive and the insulator thin films. The 3 at.% gallium

doped ZMO:Ga target ceramics were prepared by using the conventional solid state reaction

methods. Then thin film of ZMO:Ga was coated on the sapphire (0001) substrates by using the

RF-magnetron sputtering methods at room temperatures. The as-coated ZMO:Ga thin films were

post annealed in the temperature range from 500°C to 1000°C at air atmosphere. The structural

and optical properties of ZMO:Ga thin films were analyzed by using the X-ray diffraction analysis,

the scanning probe microscopy and the UV-Vis range optical transmittances. The electrical

properties of the post-annealed ZMO:Ga thin films were investigated by using the Hall Effect

measurements and the 4-wire surface conductivities. As the annealing temperature is increased in

the temperature range from 500°C to 900°C, the X-ray scattering intensity of the (002) peak was

increased but the surface conductivity was decreased. The structural characteristic were considering

the homo double layers of the post annealed ZMO:Ga thin films as the insulating ZMO layer over

the conductive ZMO:Ga layer on the substrate.




P-93

Preparations of the Ba1-xEuxTiO3 Ceramics in the Nitrogen Gas Ambient

Byeong-Eog Jun1*, Minki Kim2, Seung-Min Oh2 and Jong Rim Lee1

1Department of Physics and Earth Science, Korea Science Academy of KAIST, Busan

614-1002Korea Science Academy of KAIST, Busan 614-100

The barium europium titanate Ba1-xEuxTiO3 (BRT, x = 0 ~ 1.0) ceramics were prepared in the

nitrogen gas atmospheres for the perovskite structure. It is considered that the dielectric relaxations

is due to the magneto-polarization relaxation in the low temperatures. The perovskite BET (x =

0.30) ceramics showed the ferroelectric behaviors and the Maxwell-Wagner type dielectric

relaxations in the low frequency range from 10-2 Hz to 105 Hz. We are trying to confirm the

magneto-dielectric relaxation mechanism with varying temperature below room temperature in the

nitrogen gas ambient. It is expected that there occurs the valence electron hopping between the

partially filled d-orbitals and the p-orbitals in the Ba1-xEuxTiO3 (BET) ceramics. While the charge

frustrations of Eu atoms (Eu2+ Eu3+) results in the structural changes from the perovskite to the

pyrochlore structures. In this work, we tried to review the preparation of BET (x = 0 ~ 1.0)

ceramics by using the solid state synthesis method in the nitron gas ambient during the sinter

processes. The dielectric characterizations were performed in the low frequency range at the

nitrogen gas ambient.




P-94

Optical Characterization of Semiconductor ZnxCu1-xO Nanoparticles Prepared by

Hydrothermal method

J. P. Kim1, *, S. H. Jung2, J. H. Kim1, M. G. Ha1, J. S. Bae1,

T. E. Hong1, E. D. Jeong1, K. S. Hong1, J. S. Jin1

1Korea Basic Science Institute Busan Center, Busan2Korea Basic Science Institute Gwangju Center, Gwangju

Compounds based on copper and oxygen were extensively studied immediately after the

discovery of high temperature superconductors. CuO has a monoclinic structure with C2/c space

group and Cu2O has cubic structure with Pn3m space group. Many authors have reported the

changes associated with doping of transition metal ions into CuO lattice, which have been observed

experimentally in Mn, Ni-doped CuO, Fe and Ni co-doped, Ti, Cd and Zn. Copper oxide is

considered as well-organized catalytic agent, solar technology and also a good gas sensing material.

In this study, Semiconductor ZnxCu1-xO were prepared by hydrothermal reaction method. The

phase formation processes and micorstructures were examined by high resolution X-ray diffraction

(XRD), transmission electron microscope (TEM). The chemical bonding states of nanoparticles is

measured by X-ray photoelectron spectroscopy (XPS).


P-95

Direct Adhesion of Polyphenylenesulfide Resin and Polymeric Film on Copper

by Surface Modification

Eun Hyuk Chung1, F. Nawaz Khan1,2, Tae Eun Hong1, Jong Pil Kim1, Jong-Seong Bae1,

and Euh Duck Jeong1*

1Division of High-Technology Materials Research, Korea Basic Science Institute, Busan

618-2302Organic Chemistry Division , School of Advanced Sciences, VIT University, Vellore,

Tamil Nadu, 632 014, India

Metal/polymer assemblies are employed in areas as diverse as decorative electrodes, corrosion

protection, microelectronics, molecular adhesion promoters, and facilitators of the release of metal

molds. Various surface modifications have been applied to improve adhesion properties of bivalent

metal such as copper and aluminum for electrodes terminal application and sealing for Li ion

batteries. In this study, we evaluated the effect of different solution condition and peel strength for

the adhesion of polymeric film on copper. Characterization of the copper surface was explored by

SEM, XPS and SIMS. SEM results reveal that the meaningful roughness was formed on the copper

surface in different solutions by chemical oxidation. SIMS results represent that the peel strength

was found to depend on film thickness and the composition of adhesion layer. As a result,

Metal/polymer assemblies developed in this study have superior adhesion property. Therefore, these

assemblies might be a viable candidate as a sealing technique for Li ion batteries, and will be

beneficial in reducing the process cost and increasing the safety of Li ion batteries.




P-96

Glass formation conditions and photophysical properties of the

samarium-containing binary and ternary tellurium glass ceramics

강보배1, 하명규1, 김현규1, 양호순2, 홍경수1

1 한국기초과학지원연구원 부산센터

2 부산대학교 물리학과

Although tellurium (Te)-based glasses are very important materials in the field of glass science

and technology, tellurium oxide (TeO2) is a conditional glass former that cannot form glass by

itself when quenched from the liquid or vapor state. We establish the glass formation conditions for

the binary and the ternary tellurium-based glass systems and examine the structural and the optical

characteristics of this formation. Sm3+ is used to study the spectroscopic properties of materials.

We prepare the binary and the ternary tellurium-based glasses and investigate their characteristics.

We report the glass-formation conditions, the crystallinity, and the optical characteristics of the

binary TeO2-Sm2O3 and the ternary K2O-Sm2O3-TeO2 glasses before and after heat treatment. We

prepare several tellurium-based glasses by using the conventional melt-quenching method and

establish appropriate glass-formation compositions in both glasses. We anneal glasses for 2 h at

temperatures from 360 oC to 440 oC with a 10 oC interval, respectively, and observe the

crystallinity after annealing by using an X-ray diffractometer and a scanning electron microscope.

We show that glass ceramics after heat treatment forms in single phase crystals in both glasses,

and become phosphors under near ultra-violet excitation by measuring the optical properties such as

absorption, excitation, and emission spectra.




P-97

BaTiO3 나노 입자의 소성 시 첨가제에 따른 미세구조 및 유전특성

The microstructure and the dielectric properties with additives in the sintering

of BaTiO3 nano particle

Jae Won Kang1,2, Hyo Soon Shin1*, Dong Hun Yeo1, Dae Yong Jeong2

1)Korea Institute of Ceramic Engineering and Technology 233-5, Gasan-Dong,

Guemcheon-Gu Seoul, 153-801, Korea 2)School of Materials Science and Engineering, Inha University, Incheon, 402-751, Korea

BaTiO3는 MLCC에 사용되는 대표적인 물질이며 최근 전자기기의 소형화와 초고용량화

경향에 따라 MLCC의 유전체 층 또한 박층화와 다층화되고 있다. 이에 따라 BaTiO3의 초미립

화는 MLCC의 핵심적인 기술이며 초미립의 BaTiO3를 사용함에 따라 전기적 신뢰성이 향상되

므로 유전체 층의 형성 두께의 한계가 감소할 수 있다. 그러나 나노 BaTiO3를 사용할 경우 이

들 particle의 균일한 분산이 요구되며 전기적 특성의 제어와 grain size의 제어를 위하여 다양

한 첨가제들이 첨가되어야 한다. 이들 첨가제는 소량으로 첨가되고 또한 균일한 분산이 필수

적이므로 액상 첨가제를 이용한 조성의 개발이 필요하다. 특히, 나노 크기의 원료 powder를

적용할 경우 소결시 생성되는 액상이 변화하므로 첨가제 조성의 큰 변화가 예상되지만 이러

한 원료 입자 크기에 따른 첨가제 조성의 영향에 대한 구체적인 연구는 미흡한 실정이다. 따

라서 본 연구에서는 80 BaTiO3 powder에 Dy, Mg, Mn, Cr, Si, Ba등의 첨가제들을 액상 코팅

방법으로 첨가하여 Core-shell 구조를 형성하고 첨가제 변화에 따른 나노 BaTiO3 소결체의 미

세구조 및 유전특성을 평가하였다. 이 결과를 바탕으로 80nm BaTiO3에 적합한 새로운 MLCC

조성을 최적화하고자 하였다.

Key Words : Nano BaTiO3, MLCC, Additives, Depressor, Core-shell




P-98

4상 혼합 유전체 기판 소재의 상 분율에 따른 미세구조와 기계적 강도

Chang Hyun Lee1,2, Hyo Soon Shin1*, Dong Hun Yeo1, Hyo Tae Kim1, Sahn Nahm2

1DAdvanced Materials Convergence Division, Korea Institute of Ceramic Engineering &

Technology, Seoul 153-8012Department of Materials Science and Engineering, Korea University, Seoul 136-701

LTCC는 낮은 저항의 Cu와 Ag 전극을 세라믹 기판 소재와 동시 소성하는 소재 및 공정기

술로써 적층이 용이하고 RF 특성이 뛰어나 전자기기 부품 및 기판 소재로 많이 이용된다. 그

러나 휴대용 전자기기용 부품은 이전에 전자부품들에서 요구되지 않은 고강도와 고열전도도

같은 물리적 특성이 요구되고 있다. 하지만 glass 상을 포함하는 LTCC 소재는 이러한 물리적

특성이 취약하다는 단점을 가지고 있다. 이를 극복하기 위하여 결정화 glass와 알루미나 filler

를 이용하여 물리적 특성을 높이고자 하는 연구들이 많이 진행되어왔다. 그러나 여러 가지 결

정상의 공존에 따른 상분율과 물성의 관계에 관한 연구는 거의 보고되지 않았다. 따라서 본

연구에서는 Anorthite glass, Anorthite 결정, Diopside 결정 및 알루미나 상이 공존하는 조성 영

역을 찾고자 하였으며 이때 각각의 상분율 변화에 따른 기판 소재의 물리적 특성을 비교하고

자 하였다. 소결한 시편은 FE-SEM을 이용하여 미세구조를 확인하였고, X-선 회절분석을 이용

하여 상 분율을 분석하였으며 각 조성은 3점 곡강도를 측정 평가하였다.




P-99

ZnO-B2O3계 glass 첨가에 따른 Ca[Li1/3Nb2/3)0.8Ti0.2]O3-δ

세라믹스의 마이크로파 유전특성

Chi-Seung In1,2, Dong-Hun Yeo1*, Hyo-Soon Shin1, Sahn Nahm2

1Engineering Ceramic Team, Korea Institute of Ceramic Engineering & Technology,

Icheon 467-843, Korea2Dept, of Materials Science and Engineering, Korea University, Seoul 136-701, Korea

이동통신 단말기의 발달로 소형화, 고기능화가 요구되면서 저손실 특성을 지닌 마이크로

파 유전체가 고주파 통신용 부품들이 널리 이용되고 있다. 이러한 마이크로파 유전체는 고주

파 부품의 복합화 경향에 따라 Ag, Cu 전극과 동시소성이 가능하여야 하며, 다양한 유전율 대

역에서 낮은 손실을 갖는 소재가 요구되고 있다. 유전율 40대역에서 품질계수가 16000, τf 10

으로 우수한 마이크로파 유전특성을 지닌 Ca[(Li1/3Nb2/3)0.8Ti0.2]O3-δ 조성은 소결온도가 1175 로

높아 Ag 전극과 동시소성이 어렵다. 따라서 본 연구에서는 Ca[(Li1/3Nb2/3)0.8Ti0.2]O3-δ 조성에

ZnO-B2O3계 glass를 첨가하여 소결온도를 900 이하로 낮추고 우수한 마이크로파 유전특성을

나타내는 조성을 찾고자 하였다. CLNT와 glass 함량 변화에 따른 소결거동, 결정상, 그리고 미

세구조를 확인한 후, 그에 따른 유전특성 변화를 관찰하여 유전체 필터 소재로서의 적용 가능

성을 확인하였다.




P-100

Influence of some metal electrodes on dielectric properties of PTC ceramic

thermistor

Myoung Pyo Chun1*

1Korea Institute of Ceramic Engineering and Technology (KICET), Seoul 153-801,

Republic of Korea

The influence of three different metal electrodes on the electrical and dielectric properties was

investigated with XRD, TEM and impedance analyzer. Two electrodes, Ni-Cu/Ag and Al/Ag, were

deposited by sputtering method and the other electrode, Ag-Zn, was formed by thick film method.

Resistivity at room temperature is 28 , 104 and 253 for Ni-Cu/Ag layered electrode,

Ag-Zn electrode and Al/Ag layered electrode, respectively. From the temperature dependence of

dielectric constant, Curie temperature is different among three metal electrodes with 117oC, 108oC

and 253oC for Ni-Cu/Ag layered electrode, Ag-Zn electrode and Al/Ag layered electrode,

respectively, which seems to be related with thermal residual stress applied by thermal mismatch

between ceramic and metal layers. Thin film Ni-Cu/Ag layered electrode with lower thermal

residual stress exhibited better electrical and dielectric properties than two other ones.



P-101

High Performance Lead Free Piezoelectric Ceramic Composite

S. M. Jang* and S. J. Jeong

Korea Electrotechnology Research Institute, Changwon 642-120

In view of the current demand for global environmental protection, lead-free materials are an

important topic in studies of piezoelectric materials. Sodium-potassium-niobate (Na,K)NbO3 and

bismuth-sodium-titanate (Bi0.5Na0.5)TiO3 systems are promising ceramic families, which might soon

replace lead-based systems.

For better performance, the concept of Bismuth-based ceramic/ceramic composite was proposed.

The composite was made of relaxor matrix with ferroelectric inclusion. The phase transition was

induced by applying an external field for relaxor grains, resulting in large polarization change and

strain.




P-102

The study of thermoelectric properties in cobalt silicide/silicon thin film

thermoelectric devices

Soojung Kim1,2, Hyundal Jung1, Wonchul Choi1,3, Junsoo Kim1, Dongsuk Jun1,

Taehyoung Zyung1,2 Taekwang Kim1, Eun-su Nam1 and Seungen Moon11,*

1Energy Harvesting Devices Research Section, ETRI, Daejeon 305-700, Korea2Department of Advanced Device Technology, UST, Daejeon 305-350, Korea

3Department of Electrical Engineering, KAIST, Daejeon 305-701, Korea

For the improvement of the energy conversion efficiency in thermoelectric power devices, the

low dimensional thermoelectric materials are studied in many groups. Recently, the specially

designed silicon thin films (SiTFs) including a repeating hole patterns exhibited lower thermal

conductivity and higher ZT value because the phonon scattering increased at interfaces. [1, 2] Here,

we specially designed silicon thin film including the patterned cobalt silicide and compared the

thermoelectric properties of silicon thin film with the cobalt silicide/silicon thin film. The patterned

cobalt silicide can protect reduce the thermal conductivity by scattering the phonon. Also, the

structure is able to enhance Seebeck coefficient because of the high energy carriers which penetrate

the energy barrier between silicon and silicide. Therefore, the figure of merit ZT value can be

increased by this structure. The size width and length of silicon/silicide thin film was set to 20

× 40 , thickness was 70 nm and the implantation dose was × . And then, the 70 nm

diameter cobalt-silicide patterns having interval 140 nm were formed in silicon thin film. As a

results, the maximum seebeck coefficient was 232.03 /K and power factor was

which are higher than that of 70 nm silicon thin film. This is the first study to show that the

silicon/silicide thin film can be used for thermoelectric material.

[References]

1. Yu, J.-K., Mitrovic, S., Tham, D., Varghese, J., Heath, J. R., “Reduction of Thermal Conductivity in

Phononic Nanomesh Structures”, Nat. Nanotechnol., 5, 718-721 (2010)

2. Tang J., Wang H. T., Lee D. H., Fardy M., Huo Z., Russell T. P., and Yang P., “Holey Silicon as

an Efficient Thermoelectric Material”, Nano Lett., 10, 4279-4283 (2010)



P-103

Thermoelectric properties of sputtered silicon membrane in vertical direction

Junsoo Kim1, Wonchul Choi1,3, Soojung Kim1,2, Taekwang Kim1, Hyundal Jung1,

Dongsuk Jun1, Taehyoung Zyung1,2, Seung-Min Lee4, Eun-su Nam1 and Seungen Moon1,*


3Department of Electrical Engineering, KAIST, Daejeon 305-701, Korea4Hanbeam co., Suwon, 443-270, Korea

Silicon thermoelectricity has been widely researched to replace the conventional thermoelectric

materials, for instance, bithmuth telluride because that kind of materials are too rare and expensive

to commercialize1. To enhance the thermoelectric properties, nano-technology has been extensively

applied due to the fact that the nano-sized materials that can scatter the phonon by acoustic phonon

mismatch or geometrical nano-patterns without loss of electrical conductance so the silicon which is

most convenience to fabricate in nano-size and also has thermoelectricity becomes promising

materials for alternative material of bithmuth telluride2. However, the thermoelectricity of vertical

direction of the thin silicon membrane, the basic structure of silicon thermoelectric device, has

rarely been reported due to the difficulty of measuring the small voltage and temperature

differences. Here, we introduce the MEMS technique to measure the thermoelectric properties of

silicon nano-membrane with fine lithography techniques. To minimize the contact resistance and

extract the reliable signals, we designed 6 layers including TCR(Temperature Coefficient of

Resistance) sensors, insulating layers, heater, and silicon membrane using photo-lithography and lift

off process. The TCR and the Seebeck voltage are measured at the room temperature with high

vacuum environment to avoid heat loss by convection. The signals have sufficient reliability and

low errors, and finally Seebeck coefficient can be calculated. This technique provides easy and

precise route to measure the thermoelectric properties of membrane type of various thermoelectric

materials using conventional MEMS technique.

[References]

1. Yu, J.-K., Mitrovic, S., Tham, D., Varghese, J., Heath, J. R., “Reduction of Thermal Conductivity in

Phononic Nanomesh Structures”, Nat. Nanotechnol., 5, 718-721 (2010)

2. Z. Li, S. Tan, E. Bozorg-Grayeli, T. Kodama, M. Asheghi, G. Delgado, M. Panzer, A. Pokrovsky, D.

Wack, and K. Goodson, Nano Lett. 12, 3121–3126 (2012)



P-104

Low Power Consumption and High Sensitive Micro Alcohol Gas Sensor based

on Co-planar Micro-heater and Screen Printing Technique

S. E. Moon1*, T. K. Kim1, J. S. Kim1, W. C. Choi1, B. H. Park2, J. C. Kim2, J. J.

Jung3 and D. J. Yoo3

1Information & Communications Core Technology Research Laboratory, ETRI, 138

Gajeong-ro, Yuseong-gu, Daejeon 305-7002Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 143-701

3Sentech Korea, Sinchon-dong 21-6, Jimokro 75-gil, Paju-Si, Gyeonggi Do, 413-170

Small scale, low power consumption and high sensitive alcohol gas sensor based on SnO2

powders was fabricated by using CMOS compatible MEMS process. High-quality poly-crystalline

SnO2 based powders were made by using co-precipitation method. Their structural properties were

confirmed by using XRD, EDAX, and SEM. To activate the chemical absorption and desorption for

alcohol gas, micro-heater was embedded in the micro gas sensor, which was made by using

CMOS-MEMS process. To acquire the simple fabrication and low fabrication cost, micro-heater and

sensing electrode was located in the same plane. The response of the micro gas sensor was 0.2 for

4 ppm alcohol with lower power consumption (35 mW) than that of the commercial alcohol gas

sensor.




P-105

-20 -15 -10 -5 0 5 10 15 20 25 3010-15

10-13

10-11

10-9

10-7

10-5

10-3

sat

Vd = 0.1 V

(b)

I ds (A

)

Vg (V)

Vd = 15 V

lin

0

10

20

30

40

50

60

Mob

ilti

y,

(cm

2 /V·s

)

Fabrication and Field Effect Electronic Properties of Amorphous ZnO-SnO2

Superlattice Thin Films

Su-Jae Lee, Chi-Sun Hwang, Jae-Eun Pi, and Kyoung-Ik Cho

Smart I/O platform Research Department, ETRI, Taejeon, Korea

Amorphous ZnO-SnO2 superlattice thin films consisting of ZnO and SnO2 layers were

produced by alternating the pulsed laser ablation of ZnO and SnO2 targets, andtheir structural and

field effect electronic transport properties were investigated as a function of the thickness of the

ZnO and SnO2 layers. The performance parameters of amorphous multilayered ZnO-SnO2

superlattice thin film transistors(TFTs) are highly dependent on the thickness of the ZnO and SnO2

layers. The highest electron mobility of 43 cm2/V s, a low subthreshold swing of a 0.22V/dec.

threshold voltage of 1V, and a high drain current on-to-off ratio of 1010 were obtained for the

amorphous multilayered ZnO(1.5nm)-SnO2(1.5nm) superlattice TFTs, which are enough to operate

next-generation microelectronic devices. These results are presumed to be due to the unique

electronic structure of an amorphous multilayered ZnO-SnO2 superlattice film consisting of ZnO,

SnO2 and ZnO-SnO2 interface layers.

Fig. 1. (a) High-resolution cross-sectional STEM images and (inset) SAED patterns, and (b)

Transfer Ids-Vg characteristics and the filed effcct electron mobility(m) of amorphous ZnO-SnO2

superlattice thin films




P-106

ALD 방법으로 증착된 Al2O3 박막의 열전도도 측정

Wonchul Choi1,3, Soojung Kim1,2, Hyundal Jung1, Junsoo Kim1, Dongsuk Jun1,

Taehyoung Zyung1,2, Eunsoo Nam1, Seungmin Lee4, and Seungen Moon1,*


3Department of Electrical Engineering, KAIST, Daejeon 305-701, Korea4Hanbeam Co. Suwon 443-270, Korea

최근 반도체 기술이 발달함에 따라서 MOSFETs의 절연막에 대한 관심이 늘어나고 있다.

Metal gate 영역과 silicon의 사이에 존재 하는 절연막은 SiO2의 높은 퀄리티로 현재까지 소자

의 사이즈 축소에 큰 영향을 끼쳐 왔다. 하지만 사이즈가 점점 더 작아지면서 SiO2 박막의 두

께에도 한계가 오자 high-k 물질로 이를 대체 하려는 시도가 이어져 왔다.1 High-k 물질을 높

은 순도 및 커버리지를 위하여 ALD로 증착 하려는 노력이 지난 20년간 이어져 왔다. 하지만

ALD로 증착된 high-k 물질에 대한 열 물성에 대한 분석은 충분히 이루어지지 않았다. 이는 박

막의 열전도도 측정이 벌크 물질의 측정과는 다르며 매우 까다롭기 때문이다. 박막의 열전도

도를 측정하기 위해서는 벌크 물질과는 다른 방법이 요구 된다. 본 연구에서 Al2O3 박막의 열

전도도를 측정하기 위해서 우리는 3ω 방법을 이용하여 열전도도를 측정 하고자 한다. 3ω 방

법은 박막의 열전도도를 측정 하는 방법중에 널리 알려진 방법으로써 많은 연구가 이루어지

고 있다.2 이 방법을 이용하여 다양한 온도 영역에서의 Al2O3 박막의 열전도도를 측정 하였다.

ALD 방법으로 증착되어 비교적 높은 밀도를 갖는 Al2O3 박막의 열전도도 특성을 알아보고자

한다. 증착된 박막의 밀도 및 두께 등을 분석 하였다. 이는 MOSFET소자의 gate 절연막으로

사용될때 열적 특성을 분석을 가능하게 하여 Al2O3를 gate 절연막으로 사용하는 MOSFET의 열

분석에 도움을 줄 것으로 기대 된다.

[References]

1. Zhu, W.J., Ma, T.-P., Tamagawa, T., Kim, J., Di, Y., "Current transport in metal/hafnium oxide/silicon

structure", Electron Device Letters, IEEE, 97 - 99 Volume: 23, Issue: 2, Feb. 2002

2. Jiezhu Jin, Mohan P. Manoharan, Qing Wang, and M. A. Haque, "In-plane thermal conductivity of

nanoscale polyaniline thin films", APL, 95, 033113 2009



P-107

[그림 16] PDMS의 음속도의 압력에 따른

의존성.

고압 브릴루앙 산란을 이용한 Polydimethylsiloxane의 고압특성 분석

신선협1, 고재현1*, 고영호2, 김광주2

1200-702 강원도 춘천시 한림대학교 전자물리학과2305-152 대전광역시 유성구 국방과학연구소 4본부 2부

Polydimethylsiloxane(PDMS)는 실리콘 기반 유기 고분자의 일종으로써 압전 소자를 포함해

광범위한 분야에 적용되고 있는 재료로 잘 알려져 있다. 이런 재료의 적절한 응용을 위해서는

다양한 열역학적 변수의 광범위한 변화 하에서 다양한 물성을 획득해야 한다. 본 연구에서는

PDMS의 고압 환경 하에서의 탄성데이터를 고압 브릴루앙 산란법을 이용해 구하였다. 브릴루

앙 산란법은 응집물질 내 음파의 속도를 측정하여 물질의 굴절률, 탄성 계수 및 비정질 물질

의 경우에는 밀도까지 파악 할 수 있는 실험 방법이다. 압력은 물질의 밀도를 증가시키면서

원자간 퍼텐셜(interatomic potential) 및 이에 따른 탄

성 특성에 커다란 변화를 유도하기 때문에 음속도-

압력 등 다양한 특성을 압력에 대한 함수로 구할

수 있다. 본 연구에서는 압력을 주는 장치로

Diamond anvil cell(DAC)을 활용하여 0~10 GPa의 압

력 범위에 걸쳐서 브릴루앙 산란실험을 진행하였다

[1]. [그림 1] 에서와 같이 음속도는 압력 인가에

따라 현저하게 증가하는 형태를 보였고 굴절률은

상압에서 n 1.4값과 10 GPa에서 n 1.6의 값을 얻

었다. 이러한 데이터 분석을 통해 PDMS의 압력에

따른 굴절률 데이터를 구하였다.

* 본 연구는 방위사업청과 국방과학연구소의 연구

지원에 의한 것임을 밝힙니다.

[1] J. H. Kim, J. -Y. Choi, M. -S. Jeong, J. -H. Ko, M. Ahart, Y. H. Ko, and K. J. Kim, J. Korean

Phys. Soc. 60, 1419-1423 (2012).


Contact Phone : +82-33-248-2056


P-108

-200 0 200 400 600 800 100048

50

52

54

Bril

loui

n S

hift

(GH

z)

Temperature (oC)

LA mode Ta mode

0

1

2

3

4

FW

HM

(G

Hz)

Phase Transition Behaviors of Lead-Free (NaBi)TiO-BaTiO Single

Crystals Studied by Inelastic Light Scattering Spectroscopy

Byoung Wan Lee1, Jun Ho Ryeom1, Jae-Hyeon Ko1, Xiaobing Li2 and Haosu Luo2

1Department of Physics, Hallym University, Hallydaehakgil 1, Chuncheon 200-702, Korea2Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 201800, China

Lead-free piezoelectric materials have recently attracted great attention due to their

environmentally-friendly aspect in spite of the fact that their piezoelectric performances are

generally inferior to those of lead-based piezoelectrics, such as Pb(Zr1-xTix)O. It is of

paramount importance to understand the nature of phase transition behaviors of these materials

in order to get more insights into the way how we can improve the piezoelectric

performances of lead-free piezoelectric materials. Brillouin scattering spectrum of 0.95(NaBi

)TiO-0.05BaTiO (NBT-BT) single crystals was investigated in a wide temperature range

along different crystallographic axes. The crystals were grown by carefully controlled

top-seeded solution growth method[1], and the Brillouin spectrum was measured by using

conventional tandem 6-pass Fabry-Perot interferometer [2]. The temperature dependence of the

longitudinal acoustic (LA) mode frequency showed softening over a large temperature range,

which was most substantial for the LA mode propagating along the [100] direction. The onset

temperature of the mode softening was approximately 800 , and the LA mode frequency

exhibited a minimum near 250 and then increased on further cooling. This softening of

the LA mode was accompanied by substantial increase in the half width, as well as growth

of the quasielastic central peak. The acoustic damping also became the largest for the LA

mode along the [100] direction. These acoustic

anomalies indicate the formation and evolution of

noncentrosymmetric polar clusters in the

paraelectric phase of NBT-BT single crystals.

These acoustic behaviors will be compared to

other electric properties such as dielectric

constant.




P-109

Phase transition behaviors of PbZr0.8Ti0.2O3 single crystals as revealed

by elastic anomalies and central peaks

Min-Seok Jeong1, Jae-Hyeon Ko1*, Seiji Kojima2, Alexei A. Bokov3, Xifa Long3,

and Zuo-Guang Ye3

1Dept. of Physics, Hallym Univ., Chuncheon, Gangwondo 200-702, Korea2Institute of Materials Science, Univ. of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan

3Dept. of Chemistry and 4D LABS, Simon Fraser Univ., Burnaby, BC V5A 1S6, Canada

The acoustic phonon and central peak behaviors of PbZr0.8Ti0.2O3 single crystals were

investigated by Brillouin light scattering. The Brillouin frequency shift of the longitudinal acoustic

mode showed a substantial softening at the Curie temperature (~305oC) and the tilting phase

boundary (~127oC). The transverse acoustic mode appeared at the Curie point, indicating a clear

structural phase transition. Fig. 1 shows the temperature dependence of the intensity and the full

width at the half maximum (FWHM) of the quasi-elastic central peak of PbZr0.8Ti0.2O3. The change

in the intensity and FWHM has strong correlation with the two structural phase transitions. The

decrease in the FWHM indicates the slowing down behavior of the relevant polarization

fluctuations.

Fig.1 Temperature dependence of the intensity and the FWHM of the quasi-elastic central peak.


Contact Phone : +82-33-248-2056


P-110

Instability of Reset Parameters Due to Intrinsic Property of Conducting

Filaments Formed at Low Compliance Current in Unipolar Resistance

Switching

Sang-Chul Na1, Keundong Lee2, Min Chul Chun1, Young-Sun Kwon1, Hye-Jin Shin1, Ji

Seok Im1, Sangik Lee2, Bae Ho Park2 and Bo Soo Kang1*

1Department of Applied Physics, Hanyang University, Ansan 426-7912Division of Quantum Phases & Devices, Department of Physics, Konkuk University,

Seoul 143-701

Numerous studies on the resistance switching (RS) have been intensively conducted due to the

great potential of the application to the next-generation nonvolatile memory. There are two

switching processes in the RS, set and reset processes. The reset process means a resistance

transition from the low resistance state (LRS) to the high resistance state (HRS), while the set

process stands for a reverse reaction. In the point of practical view, higher resistance of the LRS

(RL) which is made by setting low compliance current (CC) is preferred due to low power

consumption for the reset process. However, it is generally known that the reset current (Ireset) and

voltage (Vreset) has a wide distribution when the RL is relatively high. This fact is one of serious

problem that hinder the memory application.

In this study, the reset parameters and the RL depending on CC were investigated in a

Pt/NiO/Pt thin film showing the unipolar resistance switching. Controlling CC was properly

employed to manage the connectivity of the conducting filaments (CFs). The Ireset and the Vreset at

low CC seriously fluctuated. We proposed two possibilities, the overshoot current during the set

process and an intrinsic problem coming from the CFs formed at low CC, to explain the physical

origin of the instability of the reset parameters at low CC. Combining the simple simulation and

the results eliminated the overshoot current, we could conclude that the Ireset and the Vreset fluctuated

because of the number and width variations of the CFs at low CC.




P-111

The Effects of Etch Stopper Layer on Electrical Properties of Tin monoxide

Thin Film Transistors Prepared by RF Magnetron Sputtering

J.-Y. Kim1, J.-M. Song2, K. M. Yu1, B. S. Bae1, and E.-J. Yun2,3*

1Dept. of Display Engineering, Hoseo University, Asan, 336-7952Dept. of System Control Engineering, Hoseo University, Asan, 336-795

3Dept. of Information and Communication Engineering, Hoseo University, Asan, 336-795

Recently, amorphous oxide semiconductors (AOSs) have attracted extensive attention from many

researchers. Many studies related to AOS-based thin-film transistors (AOS-TFTs) have also been

reported. The use of AOS-TFTs is expected to be a promising solution to meet market

requirements because they have a high field-effect mobility comparable with that of a-Si TFTs and

low production costs comparable with those of poly-Si:H TFTs. However, AOS-TFTs have been

limited to the n-type channel type because they have superior n-type characteristics compared to

p-type ones. Therefore, p-type AOS-TFTs are still at the initial research stage. The use of

complementary metal oxide semiconductor (CMOS) circuits composed of p- and n-channel TFTs is

necessary for fabricating high-performance integrated circuits (ICs) on glass substrates. Periphery

circuits on glass substrates, such as gate-driver ICs and data-driver ICs, have become an essential

part of high-performance display devices. Therefore, the development of p-channel AOS-TFTs is

necessary for making oxide semiconductor technology practical. A tin monoxide (SnO) has been

received a particular attention because of its high possibility in obtaining high quality p-type AOSs.

In this study, we fabricated p-type SnO-based TFTs by a more TFT-industry-compatible sputtering

from a SnO target. Then, some TFTs were post-annealed at 300 °C in N2 ambient. We used the

etch stopper layer (ESL), which acts as a passivation layer, to protect the surface of the SnO

channel layer. We systematically compared the time-dependent device properties of TFTs with ESL

to those without ESL. This comparison gave insight on the effect of ESL on the electrical

properties and the long-time stabilities of the SnO-TFTs.


Contact Phone : 010-2661-8005 (041-540-5675)


P-112

A Study on the High Temperature-dependence of Electrical Properties in

Solution-deposited Zinc Tin Oxide Thin Film Transistor Operated in the

Saturation Region

K. M. Yu1, B. S. Bae1, and E.-J. Yun2*

1Dept. of Display Engineering, Hoseo University, Asan, 336-7952Dept. of Information and Communication Engineering, Hoseo University, Asan, 336-795

Nowadays, solution-processed amorphous zinc tin oxide (a-ZTO) thin films have attracted notable attention as a channel layer in fabrication of flexible low-cost roll-to-roll printed thin film transistors (TFTs) because of their high field-effect mobility, which is possibly larger than 25 cm2/Vs, and their simplicity, low-cost, high throughput, and non-toxicity. a-ZTO thin films also possess very interesting charge transport characteristics which range from thermally-activated transport at low mobility and low carrier densities to extended state (or band) transport at high mobility, large carrier densities and low temperatures. Indeed, a-ZTO is one of the most interesting semiconductor materials in terms of charge transport, as it is at the cusp between thermally activated and band transport, exhibiting a mobility edge. a-ZTO is also the first amorphous material that possesses such a range of transport behavior as a function of field-induced carrier density. Therefore, a full picture of charge transport in this unique a-ZTO thin films needs to be developed. Moreover, there have been no clear reports of band transport and documentation of mobility edge behavior in any solution-processed amorphous semiconductor. Thus, in this paper, we investigated charge transport studies at temperatures in the range of 303 402 K in the solution-deposited a-ZTO TFTs operated in the saturation region. The developed TFTs had a bottom-gate and top contact structure, which used a heavily-doped Si wafer and a 300-nm-thick SiO2 as a gate electrode and a gate insulator layer, respectively. The channel width and the channel length of TFTs were 1500 and 100 µm, respectively. As a ZTO channel layer, zinc acetate dehydrate and tin chloride were mixed in 2-methoxyethanol to form a sol-gel solution mixture stabilized by an ethylamine. The 40-nm-thick ZTO channel layers were obtained by annealing at 600 °C for 1 hour in a furnace. In a-ZTO channel, the trap release energy (ETR) was estimated using Fermi-Dirac statistics and the Maxwell-Boltzmann approximation. The decreasing the ETR with increasing density of trap states (ns) can be understood by a shift of the Fermi level toward the mobility edge and the shapes of ns fit very well to exponential function, indicating that the experimental data in the insulating regime well agreed with the modified multiple trap and release model and show the thermally activated behavior which is related to the increase of mobility with increasing temperature. It was found that the use of Fermi-Dirac statistics instead of Maxwell-Boltzmann statistics is important in accurately determining the ETR.


Contact Phone : 010-2661-8005 (041-540-5675)


P-113

High Temperature Dielectric Relaxations in BiFeO3-(Bi,K)TiO3 Ceramics

Jung Hwan Kim1, Jeong Seog Kim2, Wook Jo3, Chae Il Cheon1∗

1Department of Materials Science & Engineering and 2Department of Digital

DisplayEngineering, HoseoUniversity, Asan, Chungnam 336-795 Korea3Ulsan National Institute of Science and Technology, Ulsan 689-798, Korea

BiFeO3-(Bi,K)TiO3 (BF-BKT) ceramics has been reported to demonstrate outstanding

ferroelectric and piezoelectric properties; a large remanent polarization of about 50μC/cm2 and a

moderate electro-mechanical coupling factor (k33) of 0.3~0.35 at phase boundaries between

ferroelectric rhombohedral and pseudocubic. However, there is large variance among

temperature-dependent dielectric properties reported in literatures. Relaxor-like dielectric properties,

i.e., broad dielectric maximum with frequency dispersion, have been observed in the pseudocubic

composition range and claimed to originate from nanosized polar domains. And a Maxwell-Wagner

type dielectric relaxation was also observed in a BF-BKT ceramic below 300oC in BF-rich

rhombohedral compositions.

The dielectric relaxations due to extrinsic effects have been observed in many perovskite

titanates compounds; Maxwell-Wagner relaxation at grain boundary and/or contact electrode in

ferroelectric super-lattice thin films and CaCu3Ti4O12 (CCTO), and Debye-type dipolar relaxation due

to oxygen vacancies in BaTiO3, (Pb,La)TiO3, Pb(Mg,Ni)O3-PbTiO3, and CCTO at 300oC~700oC. The

extrinsic dielectric relaxations are expected in BF-BKT ceramics as well and could make an

understanding on the temperature-dependent dielectric behavior difficult.

In this work, the temperature-dependent dielectric behavior was investigated in BF-BKT

ceramics. Dielectric constant and the corresponding loss factor were measured in the temperature

range of RT to 650oC at various frequencies. Extrinsic dielectric relaxations were observed at

around 300~600oC. Impedance spectroscopy was utilized for understanding the origins of the

relaxations. Dielectric relaxations in BF-BKT ceramics sintered under various atmospheres such as

air, oxygen, and nitrogen have been compared to clarify the origins of the extrinsic dielectric

relaxations.




P-114

First-principles Investigation of Bistability in Ga- and In-doped CdF2

M. S. Kim1* and C. H. Park1,2

1Research Center for Dielectric and Advanced Matter Physics, Department of Physics,

Pusan National University, Busan 609-7852Research Center for Dielectric and Advanced Matter Physics, Department of Physics

Education, Pusan National University, Busan 609-785

In II-V and II-VI znic blende semiconductors, one of the well-known phenomena is a

bistability in which a dopant atom has both highly localized deep and shallow states. Amazingly,

the same type of bistability is reported for Ga- and In-doped CdF2 in fluorite structure and the

discovery of bistability in large-band-gap materials can open the way for novel applications such as

photorefractive medium. However, the theoretical understanding is still controversial. Here, we report

the electronic structure of Ga- and In-doped CdF2, and the bistability of atomic structure around In,

Ga, and Tl in CdF2, based on the screened hybrid functional method.



후원업체 소개

회사명 (한맥전자(주))대 표 자 한맥전자(주)전 화 02-467-7447 팩 스 02-467-6816이 메 일 [email protected] 홈페이지 http://hanmacco.com주 소 서울시 성동구 성수1가 2동 16-4번지 SK 테크노빌딩 1001호

․ 회사소개 저희 한맥전자(주)는 1988년부터 외국의 첨단 계측장비를 대학, 연구소, 반도체, 디스플레이, 정보통신, 전기, 전자 및 자동차 관련 산업체 등에 판매를 하여왔습니다.첨단 계측장비를 공급 및 기술 지원을 하면서 습득한 신기술을 바탕으로 1994년에 부설 기술연구소를 설립하여 PDP화상평가장치, 3D Laser 화상입력기 및 원격검침 장치를 개발하였습니다.미래지식 산업체의 일원으로 성장하기 위해 최선을 다하고 있으며, 신속한 기술지원으로 고객으로부터 신뢰받고 주주와 종업원에게 이익과 만족을 주며 지속적으로 성장하는 건강한 회사가 되고자 합니다.

․ 전시품명1) High Voltage Power Amplifier2) Function Generator

․ 제품특징1) High Voltage Power Amplifier

0 - 50kV의 넓은 대역의 Line-upApplication PIEZO, Ferro-electric, Hysterisys

2) Function Generator

제24회 유전체물성 심포지엄 제16회 강유전체 소자 소재...

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