humberto foronda

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Humberto ForondaHumberto Foronda

Materials Science and Engineering, University of Florida, Gainesville, FL, USA

IRES 2011: Undergraduate Research in IRES 2011: Undergraduate Research in Leoben, AustriaLeoben, Austria

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Support: NSF OISE-0402066, DMR-0746902, and OISE-0755170, Army Research Office W911NF-09-1-0435.

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Leoben,Austria

Population: 25,227Official Language: German

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Montanuniversität Leoben

Specializes in Mining, Metallurgy, and MaterialsNumber of Students: 2,764

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Life at the Institute• Insititut für Struktur und Funktionskeramik

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Research• Investigation of Sodium Bismuth Titanate

with Iron and Manganese at different percentages with an electron microprobe

• Raman Spectroscopy on various compositions of NBT-BT processed at the University of Florida and Darmstadt

• Investigation of crack propagation in Vickers Indentations on conditioned Lead Zirconate Titanate

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Electron Microprobe

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NBT-FeNBT-Fe 0.5%

NBT-Fe 2.0%

Fe

Feclusters

Grain Pullout

Grain Pullout

•Electron microprobe image (left). Same image with focus on Fe(right)

•0.5% noticeably homogenous throughout sample

•2.0% forms Fe-rich deposits(clusters) around pores, noticeably inhomogeneous

clusters

Grain Pullout

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NBT-MnNBT-Mn 0.5%

NBT-Mn 2.0%

Mn

Mn

Grain Pullout

Grain Pullout

clusters

•Electron microprobe image(left).Same image with focus on Mn (right)

•0.5% noticeably homogenous throughout sample

•2.0% has Mn-rich deposits, noticeably inhomogenous

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Magnified Images of 2% Mn-NBT

Grain pullout

cluster

cluster

Grain pullout

Mn

Grain pullout

Na

Reduction in Bi

Grain pullout

Bi

• Original image of magnified surface of NBT-Mn 2%

• electron microprobe conducts search on Mn, cluster of Mn, inhomogeneous

• Electron microprobe conducts search on Na, cluster of Na,

• Electron microprobe conducts search on Bi, reduction in bismuth.

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Raman Spectroscopy•Examines vibrational modes in a sample•Sample was measured with a source of monochromatic light, recording only the inelastically scattered photons•Incident Photon can be absorbed by molecule (Stokes Scattering) •Molecule can lose energy (Anti-Stokes Scattering)

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Raman Spectra for NBT-BT

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Raman for NBT-BT• Raman Spectra is plotted raw data.• Analyzing data through peak fitting helped us find

transition temperatures• According to literature on NBT-based materials, the

mode at 620 cm-1 represents vibrations of the BO6 octahedra occurring along the c-axis, showing a change in the symmetry or tilting of the octahedra

% BT Transition Temp in Darmstadt (Celsius)

Transition Temp in UF (Celsius)

6 205 265

7 225 285

9 225 265

• expect to see it as an anomaly in the peak position of the mode at 620 cm-1

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IndentationsE-Field Poled PZT

sample with Vicker’s Indentation (Anisotropic)

Cracks parallel to E-field shorter due to energy lost when domains switched from perpendicular to parallel.

• Life expectancy of poled samples were investigated.

• Repeated crack length measurements which were conducted two years ago in order to compare and discover a potential aging effect.

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Recorded MeasurementSample Parallel(μm) Normal(μm) Parallel (μm) Normal (μm) Parallel (μm) Normal (μm)PZT_T_P01 Indenation 1 167 276.5 173.4 287.9 166.2 274.6

PZT_T_P01 Indenation 2 159.3 282.6 160.3 292.3 155.9 269.5

PZT_T_P01 Indenation 3 165.3 273.7 161.6 278.3 156.0 272.6

PZT_T_P01 Average 166.2 275.1 165.1 286.2 159.4 272.2

PZT_T_P02 Indenation 1 193 206.3 204.7 225.0 182.13 229.2

PZT_T_P02 Indenation 2 190.8 213.4 185.2 227.6 179.31 231.58

PZT_T_P02 Indenation 3 188 206.8 190.9 227.4 204.63 229.78

PZT_T_P02 Average 190.6 208.8 193.6 226.7 188.69 230.1866667

PZT_T_P03 Indenation 1 173.1 221.2 176.9 252.2 174.18 234.11

PZT_T_P03 Indenation 2 180.8 227.3 182.9 247.7 177.93 240

PZT_T_P03 Indenation 3 180.8 224.5 189.4 244.1 185.62 236.63

PZT_T_P03 Average 178.2 224.3 183.1 248.0 179.24 236.91

Cracked and Measured by Dr. Bermejo in 2009Cracked by Dr. Bermejo but measured by Humberto in 2011Cracked and measured by Humberto in 2011

1. Poled at 2kV/mm, heated to 150 celsius2. Poled at 2kV/mm, heated to 150 celsius, 50 MPa load3. Poled at 2kV/mm, heated to 75 celsius, 50 MPa load

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Recorded Measurements

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Future Work• Prepare NBT results from Austria for

publication

• Continue work on NBT-BT temperature dependant measurements

• Potentially continue measurements of electromechanical coupling factor