materiale electrotehnice noi
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Materiale electrotehnice noi. 1. Fenomene in materialele electrotehnice: conductia electrica si polarizarea electrica. Cuprins. Structura disciplinei Mod de notare Fenomene in materiale electrotehnice Conductia electrica Polarizarea electrica. Structura disciplinei. Bibliografie. - PowerPoint PPT PresentationTRANSCRIPT
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I Prof.dr.ing.Florin Ciuprina
Materiale electrotehnice noi
1. Fenomene in materialele electrotehnice: conductia electrica si polarizarea electrica
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Cuprins Structura disciplinei Mod de notare
1. Fenomene in materiale electrotehnice Conductia electrica Polarizarea electrica
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Structura disciplineiCapitolul Conţinutul
1 Fenomene in materialele electrotehnice1.1. Conductia electrica1.2. Polarizarea electrica1.3. Magnetizarea materialelor1.4. Pierderi in materialele electrotehnice
2 Materiale conductoare noi2.1. Materiale conductoare clasice2.2. Conductori organici si moleculari2.3. Supraconductori2.4. Materiale pentru realizarea de memristori2.5. Aplicatii moderne ale materialelor conductoare
3 Materiale semiconductoare noi3.1. Materiale semiconductoare clasice3.2. Polimeri semiconductori3.3. Materiale semiconductoare nanostructurate3.4. Aplicatii moderne (celule solare, microprocesoare de inalta frecventa, ecrane TV, laseri)
4 Materiale dielectrice noi4.1. Evolutia materialelor dielectrice4.2. Straturi subtiri4.3. Nanodielectrici4.4. Oxizi metalici4.5. Aplicatii
5 Materiale magnetice noi5.1. Evolutia materialelor magnetice5.2. Materiale magnetice amorfe5.3. Materiale magnetice nanostructurate (nanocristaline, organice)5.4. Fire si filme subtiri din materiale magnetice5.5. Aplicatii moderne (miezuri magnetice, memorii, hard-discuri, carduri magnetice)
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Bibliografie F. Ciuprina, Materiale electrotehnice noi – Planse de prezentare curs
(Master IPE), www.elmat.pub.ro/~florin/student/Master-MEN/info_MEN.html, 2009.
F. Ciuprina, Materiale electrotehnice – fenomene si aplicatii, Editura Printech, 2007
P.V.Notingher, Materiale pentru electrotehnica, POLITEHNICA PRESS, Bucuresti, 2005.
B. Streetman, S. Banerjee, Solid state Electronic Devices, Prentice Hall, 2005
L. Solymar, D. Walsh, Electrical Properties of Materials, Oxford University Press, 2004.
IEEE Transactions on Dielectrics and Electrical Insulation, Nanodielectrics, Vol.15, Nr.1, 2008
http://www.superconductors.org/.
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Mod de evaluare
Laborator: 50 p Determinari experimentale + analiza → articol stiintific = 30 p Determinari experimentale + analiza → poster stiintific = 20 p
Examen final: 50 p.
Cerinţele minimale pentru promovare: efectuarea tuturor lucrǎrilor de laborator şi acumularea a 50p.
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
1. Fenomene in materiale electrotehnice
Conductia electrica Polarizarea electrica Magnetizarea materialelor Pierderi in materialele electrotehnice
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica
1. Fenomene in materiale electrotehnice
Conductia electrica Polarizarea electrica Magnetizarea materialelor Pierderi in materialele electrotehnice
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica
Conductia electrica
a metalelor a semiconductorilor a izolatorilor
se datoreaza: electronilor (metale, semiconductori,
izolatori); ionilor (izolatori)
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica
Ce sunt electronii?
Modele - (unul) clasic
- (mai multe) cuantice
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica – Electroni in cristale
Electroni in cristale
1. Modelul clasic al electronului
2. Modele cuantice. Unde asociate electronilor
3. Sisteme de particule. Numere cuantice
4. Starile electronilor in cristale
5. Repartitia electronilor pe nivelurile benzilor permise
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica – Electroni in cristale
Electroni in cristale
1. Modelul clasic al electronului
2. Modele cuantice. Unde asociate electronilor
3. Sisteme de particule. Numere cuantice
4. Starile electronilor in cristale
5. Repartitia electronilor pe nivelurile benzilor permise
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica – Electroni in cristale
Modelul clasic al electronului
Ernest Rutherford (1871-1937)
fizician britanicNiels Bohr (1885-1962)
fizician danez
ELECTRON = bilă minusculă, de rază r ≈ 2, 82 ·
10−5 Å,
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica – Electroni in cristale
Electroni in cristale
1. Modelul clasic al electronului
2. Modele cuantice. Unde asociate electronilor
3. Sisteme de particule. Numere cuantice
4. Starile electronilor in cristale
5. Repartitia electronilor pe nivelurile benzilor permise
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica – Electroni in cristale
Modele cuantice. Unde asociate electronilor
electron unda
sau – functie de unda = solutie a ec. Schrödinger:
Louis de Broglie ( 1892 - 1987)
fizician francez
Erwin Schrödinger (1887- 1961)
fizician german
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica – Electroni in cristale
Electroni in cristale
1. Modelul clasic al electronului
2. Modele cuantice. Unde asociate electronilor
3. Sisteme de particule. Numere cuantice
4. Starile electronilor in cristale
5. Repartitia electronilor pe nivelurile benzilor permise
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica – Electroni in cristale
3. Sisteme de particule. Numere cuantice
Sisteme de particule
nuclee + electroni = sistem de N particule. starile sistemului sunt descrise de functia de unda ,
solutie a ecuatiei Schrödinger:
= densitatea de probabilitate a prezentei primeiparticule a sistemului in vecinatatea unui punct dat M1(x1, y1, z1), a celei de a doua particule in vecinatatea punctului M2(x2, y2, z2) etc.
= Π , = expresii aproximative
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica – Electroni in cristale
3. Sisteme de particule. Numere cuanticeNumere cuantice
depind in starile stationare de 4 numere cuantice:
numar cuantic principal n determina valorile energiei electronului n = 1, 2, 3, …
numar cuantic secundar l determina valorile momentului cinetic orbital si ale momentului magnetic orbital
ale electronului l = 0, 1, 2, 3, …, n-1
numar cuantic magnetic ml determina valorile proiectiei momentului cinetic orbital si ale proiectiei momentului
magnetic orbital pe o directie arbitrara (adesea directia campului magnetic exterior)
ml = 0, ±1, ±2, …, ±l numar cuantic de spin ms
determina valorile proiectiei momentului cinetic de spin si ale proiectiei momentului magnetic de spin pe o directie arbitrara (adesea directia campului magnetic exterior)
ms = ±½
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica – Electroni in cristale
3. Sisteme de particule. Numere cuantice
Numere cuantice
n, l, ml - determina o stare orbitala a electronului
n, l, ml, ms - determina o stare cuantica a electronului
Principiul de excluziune al lui Pauli:
Intr-un sistem format din particule avand numarul cuantic de spin ms semiintreg (electroni, protoni,neutroni),intr-o
stare cuantica se poate gasi o singura particula componenta a sistemului.
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica – Electroni in cristale
Electroni in cristale
1. Modelul clasic al electronului
2. Modele cuantice. Unde asociate electronilor
3. Sisteme de particule. Numere cuantice
4. Starile electronilor in cristale
5. Repartitia electronilor pe nivelurile benzilor permise
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica – Electroni in cristale
4. Starile electronilor in cristale
Ipoteze simplificatoare: electroni indiscernabili, functia de unda asociata unui electron
descrie starile oricarui electron din cristal.
cristale unidimensionale.
ioni imobili in noduri (exista, insa, o interactiune electron-ion prin intermediul campului electric produs de ioni).
exista o interactiune intre electronii studiati si campul electric produs de alti electroni.
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica – Electroni in cristale
4. Starile electronilor in cristale
Aproximatia electronilor liberi:
Ipoteze: electronii nu interactioneaza cu ionii din nodurile retelei → conditie de ciclicitate (Born): (x) = (x+L)
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica – Electroni in cristale
4. Starile electronilor in cristale
Aproximatia electronilor cvasiliberi:
Ipoteze: electronii interactioneaza cu ionii din nodurile retelei →
reflexii Bragg cand
, pentru cristalul unidimensional
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica – Electroni in cristale
4. Starile electronilor in cristale
Aproximatia electronilor cvasiliberi:
→ unde stationare:
==
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica – Electroni in cristale
4. Starile electronilor in cristale
Aproximatia electronilor cvasiliberi:
Masa efectiva a electronului:
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica – Electroni in cristale
4. Starile electronilor in cristale
Aproximatia electronilor puternic legati:
Ipoteze: functii de unda de tip Heitler-London
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica – Electroni in cristale
4. Starile electronilor in cristale
Aproximatia electronilor puternic legati:
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica – Electroni in cristale
4. Starile electronilor in cristale
Aproximatia electronilor puternic legati:
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica – Electroni in cristale
4. Starile electronilor in cristale
electroni liberi
electroni cvasiliberi
electroni puternic legati
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica – Electroni in cristale
Electroni in cristale
1. Modelul clasic al electronului
2. Modele cuantice. Unde asociate electronilor
3. Sisteme de particule. Numere cuantice
4. Starile electronilor in cristale
5. Repartitia electronilor pe nivelurile benzilor permise
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica – Electroni in cristale
5. Repartitia electronilor pe nivelurile benzilor permise
Statistica Fermi-Dirac:
E = 0, echilibru termic:
E ≠ 0, echilibru termic:
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica - metale
Conductia electrica a metalelor
metal monovalent metal bivalent
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica - metale
Conductia electrica a metalelorInfluenta temperaturii
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica - metale
Conductia electrica a metalelorInfluenta impuritatilor
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica - metale
Conductia electrica a metalelorSupraconductibilitatea
Keike Kamerlingh Onnes (1853-1926)
fizician olandez
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica - semiconductori
Conductia electrica a semiconductorilor
σ = 10-6 – 105 S/m
tip n tip p
semiconductor intrinsec semiconductori extrinseci
wi = 10-2 – 10-1 eV wi = 0.5 – 1.5 eV
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica - semiconductori
Conductia electrica a semiconductorilor intrinseci
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica - semiconductori
Conductia electrica a semiconductorilor extrinseci de tip n
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica - semiconductori
Conductia electrica a semiconductorilor extrinseci de tip p
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica - semiconductori
Conductia electrica a semiconductorilor
Influenta temperaturii si a concentratiei de impuritati
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica - semiconductori
Conductia electrica a semiconductorilor
Jonctiunea p-n
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica a izolatorilor solizi
Conductia electrica a izolatorilorCurentul prin izolator la aplicarea unei tensiuni continue:
absorbtie
t
tresorbtie
I
U
Ic
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica a izolatorilor solizi
Conductia electrica a izolatorilorCurent de absorbtie:
absorbtie
t
tresorbtie
I
U
Ic
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica - izolatori
Conductia electrica a izolatorilorMecanisme de conductie:
- electronica
- ionica
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica - izolatoril
Conductia electrica a izolatorilorIpoteze: cristal ionic conductie datorata ionilor pozitivi din interstitii
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica - izolatori
Conductia electrica a izolatorilorConductia electronica in campuri uzuale
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Conductia electrica - izolatori
Conductia electrica a izolatorilorConductia electronica in campuri intense
Strapungerea izolatorilor solizi:
electrica intrinseca prin avalansa de electroni
termica
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Polarizarea electrica
1. Fenomene in materiale electrotehnice
Conductia electrica Polarizarea electrica Magnetizarea materialelor Pierderi in materialele electrotehnice
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Polarizarea electrica
Polarizarea electrica
Polarizatie:
Tipuri de polarizare:
polarizare de deformare electronica ionica
polarizare de orientare polarizare de neomogenitate (interfaciala)
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Polarizarea electrica
Polarizarea electricaPolarizarea de deformare electronica
01010 15140 ee Pff Hz
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Polarizarea electrica
Polarizarea electricaPolarizarea de deformare ionica
01010 14130 ii Pff Hz
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Polarizarea electrica
Polarizarea electricaPolarizarea de orientare (relaxare)
01010 860 oo Pff Hz
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Polarizarea electrica
Polarizarea electricaPolarizarea de neomogenitate (interfaciala)
01020 nn Pff Hz
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Polarizarea electrica
Polarizarea electrica
Permitivitatea dielectricilor in campuri armonice
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Facultatea de Inginerie Electrica, Materiale electrotehnice noi, 2011-2012, master IPE, anul I
Polarizarea electrica
Polarizarea electrica
Permitivitatea dielectricilor in campuri armonice