The properties of a material determines what we can do with it, and extreme properties permit extreme applications. Modern computers are an example of how our control over material properties has allowed amazing new technologies.
This module covers common physical properties of materials, as well as the experimental techniques used to measure them. The language of crystallography is introduced as attention will be focused on crystals such as diamond. X-ray diffraction is invaluable for characterizing a crystal's geometric structure and orientation.
When a group of isolated atoms form a solid, some of the electrons move to a different quantum state which allows the solid to hold together. These electrons are central to the properties of the solid and so determining this "electronic structure" is key to understanding a material's properties. The quantum theory that describes this is briefly introduced, reminding students how the idea of a chemical bond can be extended to the electronic band structure of a solid.
Electronic, mechanical, thermal, optical and magnetic properties are treated. The electrical characterizations covered include experiments in which current is injected into a material through electrical contacts as well as high-frequency measurements which do not require contacts. Mechanical characteristics such as hardness and strength are studied in experiments which subject samples to external impacts and forces. Strong electronic bonds between atoms in a crystal tend to make the crystal resistant to these external forces. Similarly, these stronger bonds allow higher energy phonons, which tends to increase a material's thermal conductivity. Optical transparency is explained as arising from the electronic band-gap. Optical spectroscopy techniques are introduced, including more advanced experiments such as Fourier-transform infra-red spectroscopy. The magnetic properties of materials are of growing interest because of technological progress in areas such as spintronics. Electron paramagnetic resonance is a powerful tool for studying the magnetic properties of insulators and semiconductors.
Above: The unit cell of diamond.
By the end of the module students should:
1. Have an overview of important material properties, with a focus on three-dimensional crystals, including the use of X-ray diffraction to study geometric structure.
2. Have a theoretical awareness of the quantum mechanical theory of electronic structure and its role in determining material properties.
3. Know how to set up an appropriate program of electronic, mechanical, thermal, optical and/or magnetic measurements to investigate the properties of a material.
4. Appreciate the technological importance of these materials properties.
Lectures 1-2 (Philip Martineau)
Module overview, crystallography (lattices, perfect crystals, symmetry, geometric structure)
Lecture 3 (Philip Martineau)
Geometric structure characterization: X-ray diffraction, X-ray topography
Lecture 4 (Gavin Morley)
Electronic structure: building crystals from atoms
Lectures 5-6 (Gavin Morley)
Electronic Properties: Metals/semiconductors/insulators, intrinsic and extrinsic conductivity, relative permittivity
Lectures 7 (Gavin Morley)
Electronic characterization: Four-point probe conductivity measurements, the importance of electrical contacts (Ohmic and Schottky), contact geometries, A.C. conductivity measurements, superconductivity
Lectures 8-9 (Gavin Morley)
Magnetic properties (ferromagnetism, paramagnetism, diamagnetism) and magnetic characterization (magnetic resonance and SQUID magnetometry)
Lectures 10-11 (Claire Dancer)
Mechanical properties: hardness and strength, mechanical testing and stress and strain measurements
Lecture 12-13 (Stephen Lynch)
Optical Properties and characterization: Maxwell's equations, optical dipoles, phonons, infrared absorption, FTIR spectroscopy, the effect of the band gap on transparency, the importance of defects and dopants
Lecture 14-15 (Stephen Lynch)
Thermal properties: phonons, thermal conductivity and thermal expansion, including experimental techniques
Eisberg and Resnick, Quantum Physics of Atoms, Molecules, Solids, Nuclei, and Particles, John Wiley & Sons, ISBN-10: 047187373X, 1985
Charles Kittel, Introduction to Solid State Physics, John Wiley & Sons, ISBN-10: 047141526X, 2004
J R Hook and H E Hall, Solid State Physics, Wiley-Blackwell, ISBN-10: 0471928054, 1991
N W Ashcroft and N D Mermin, Solid State Physics, Brooks/Cole, ISBN-10: 0030839939, 1976
Stephen Blundell, Magnetism in Condensed Matter, OUP Oxford, ISBN-10: 0198505914, 2001
John Singleton, Band Theory and Electronic Properties of Solids, OUP Oxford, ISBN-10: 0198506449, 2001
Terry M Tritt, Thermal Conductivity: Theory, Properties, and Applications, Springer, ISBN-10: 1441934448, 2010