Z. Barber - Materials for devices.pdf

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Natural Sciences Tripos Part I A
MATERIALS SCIENCE
Course B: Materials for Devices
Name............................. College..........................
Dr Zoe Barber
Michaelmas Term 2012 13
Michaelmas Term 2012-13
I A
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Contents
Introduction
Synopsis
Text Books & Websites
1
2
3
Magnetic Materials
Diamagnetism, Paramagnetism
Ferro-, Antiferro-, Ferrimagnetism
Ferromagnetic Materials
Curie temperature
Magnetocrystalline anisotropy
Domain formation
Shape Anisotropy
Magnetostriction
Domain wall, Bloch wall
Ferromagnetic Hysteresis
Aside on magnetic parameters
Hysteresis loops: hard versus soft
Ferrimagnetism & Spinel Structure
Inverse Spinel Structure
36
36
37
38
38
38
38
39
39
39
40
42
42
43
43
Liquid Crystals
Nematic Liquid Crystal structure
Polarized Light
Birefringence & Polarized Light Microscopy
The Michel-Levy Chart
Extinction Positions &
Permitted Vibration Directions
Determination of Sign of Birefringence
Birefringence in Liquid Crystals
Further types of Liquid Crystals:
Smectic & Chiral Nematic
Liquid Crystal Displays
4
4
6
8
10
11
11
11
12
14
Solid Ionic Conducting Materials
(a) Diffusion Current
(b) Drift Current
Nernst-Einstein Equation
Solid State Ionic Conductors
Yttrium Stabilized Zirconia, YSZ
δ -Bi 2 O 3
Applications
1. Oxygen Concentration cell
Lambda Sensor
2. Oxygen Pump
3. Fuel Cell
The hydrogen economy
44
45
46
46
48
48
48
49
49
50
51
51
53
An Introduction to Polymer Structures
Flexible chains: conformation
How big is a polymer molecule?
Examples of common polymers
Polymer Microstructure & Properties
Crystallinity
16
17
19
20
21
22
Dielectric Properties of Materials
Polarisation Mechanisms
Polarisation & Capacitance
Dipole formation & Symmetry
Piezoelectrics
Pyroelectrics
Ferroelectrics
Polarisation & Structure
Phase Transitions in BaTiO 3
Switchable Dipoles
Dipole ordering & Domains
Reversible Polarisation, hysteresis
Applications, memory device
PZT
23
23
23
25
27
28
29
29
30
31
32
33
34
35
54
Glossary
BH1
Course B: Materials for Devices
BH1
Course B: Materials for Devices
The functional properties of materials, such as magnetism, polarization and conduction, are intimately
related to their crystal structure. Furthermore, many of these properties are also anisotropic –
meaning that they are dependent upon the specific direction within a crystal structure. It is imperative
that we understand these structure–property links in order to understand fully materials properties,
and be able to control and optimize these properties. Only through such an understanding can we
hope to exploit the full range of possible device and materials applications, keep coming up with
smaller and smaller music systems, faster computers, and overcome some of the environmental issues
currently troubling the world.
The course begins with the remarkable properties of Liquid Crystals: somewhere between liquids
(isotropic, no long range order) and crystals (anisotropic and ordered). The anisotropy of liquid
crystals leads to important optical effects, which are exploited in display technology.
BH2
Course B: Materials for Devices
BH2
Synopsis of Course B
1. Liquid Crystals & Polarized Light: rigid polymer molecules, nematic structures, the order
parameter. Plane polarized light and birefringence. Permitted vibration directions, optical path
difference & phase difference, Polarized Light Microscopy.
2. Birefringence in Liquid Crystals: the Michel-Levy chart, extinction positions, compensators.
Schlieren texture and disclinations. Smectic and chiral / cholesteric liquid crystals. Liquid Crystal
Displays.
3. An Introduction to Polymer Structure: repeated monomer units, long chain molecules,
methods of representation. Conformation, flexibility, molecular size. Side groups, tacticity,
microstructure & properties. Crystallinity in polymers.
4. Dielectrics: polarisation mechanisms, permittivity & dielectric constant, capacitance. Symmetry &
properties.
5. Polarisation; Piezo-, and Pyro-electrics : Piezoelectric motor & generator effect, pyroelectric
applications.
6. Ferroelectricity: polarisation & structure, switching, phase transitions in BaTiO 3 . Dipole
ordering & domains, domain walls, poling.
7. Ferroelectric Hysteresis & Applications: domain reversal & hysteresis loops. FE memory
devices, materials requirements. PZT phase diagram.
8. The Origin of Magnetism: electron orbitals & spin; dia-, para-, ferro-, antiferro- & ferri-
magnetism. Magnetocrystalline anisotropy, domain formation, shape anisotropy, magnetostriction.
9. Ferromagnets: domains and domain walls, ferromagnetic hysteresis. Tailoring magnetic
properties for applications. Ferrimagnetism: the spinel & inverse spinel structures & magnetite.
10. Solid Ionic Conducting Materials: conduction in solids, vacancy mediated ion hopping,
activation energy, ion flux. Diffusion current (concentration gradient) & drift current (electric field).
11. Solid State Ionic Conductors: the Nernst-Einstein equation. Arrhenius plots and ion
conductivity. Yttrium stabilized zirconia, formation of oxygen vacancies. Oxygen concentration cell.
12. Applications of Ionic Conductors: Lambda sensor, oxygen pump, fuel cells. Materials
requirements, the hydrogen economy.
BH3
Course B: Materials for Devices
BH3
Recommended Text Books & Websites
Parts of the following may be helpful:
Basic Solid State Chemistry A R West (Wiley, 2 nd edition) Pq62, and Pq62a Tripos Ref.
For polymers and liquid crystals –
Liquid Crystalline Polymers A Donald, A Windle & S Hanna (C.U.P., 2 nd edition) AN6b.140,
AN6c.140, and AN6c.140a Tripos Ref.
Physical Properties of Polymers James Mark et al (C.U.P., 3 rd edition) AN6c.135
Liquid Crystals Peter J Collings (I.O.P. Publishing, 2 nd edition) Ng134a, and Ng134b Tripos Ref.
Dielectrics, polarisation, conduction, magnetism, ceramics –
Electroceramics A J Moulson & J M Herbert (Wiley, 2 nd edition) AN2a.111
Introduction to Ceramics W D Kingery, H K Bowen & D R Uhlmann (Wiley, 2 nd ed.) AN2a.13,
and AN2a.13a Tripos Ref.
More general interest –
Materials Science and Engineering W D Callister (John Wiley, 2003, 6 th ed.) AB168a, and AB168
Tripos Ref.
Introduction to Materials Science J P Mercier, G Zambelli & W Kurz (Elsevier) AB218b, and
AB218a Tripos Ref.
Also, many of the DoITPoMS Teaching & Learning Packages:
Introduction to Anisotropy
Atomic Scale Structure of Materials
( see Single Crystals: Optical Properties )
Crystallinity in Polymers
Crystallography
Dielectric Materials
Diffusion
Ferroelectric Materials
Ferromagnetic Materials
Fuel Cells
Lattice Planes and Miller Indices
Liquid Crystals
Optical Microscopy ( look at Polarised Light )
Introduction to Photoelasticity
Piezoelectric Materials
Pyroelectric Materials
Polymer Basics
http://plc.cwru.edu Resources related to Polymers and Liquid Crystals.
Crystal Maker Software: see link on website for this course.
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