Page 10 - Microsoft PowerPoint - lecture1.ppt

1. Introduction

Classifications for solids (examples)

• Degree of order

• long range order: crystals (3D periodicity)

• long range order with extended defects (dislocations…)

• crystals with disorder of a partial structure (ionic conductors)

• amorphous solids, glasses (short range order)

• Chemical bonding – typical properties

• covalent solids (e.g. diamond, boron nitride): extreme hardness ...

• ionic solids (e.g. NaCl): ionic conductivity ...

• metals (e.g. Cu): high conductivity at low temperatures

• conductivity: metals, semiconductors, insulators, superconductors…

• magnetism: ferromagnetism, paramagnetism…

• Structure and Symmetry

• packing of atoms: close packed structure (high space filling)

• characteristic symmetry elements: cubic, hexagonal…