Solid State Physics

Chapter 1

Crystal Structure

1.1 INTRODUCTION

There are three well-recognized states of matter: solid, liquid, and gas. Solids have a definite shape and fixed volume, liquids have no definite shape but fixed volume, gases, in whichever container they are kept, occupy the whole volume of the container and their molecules randomly move with very high speed. The intermolecular separation in solids and liquids are of the order of a few Angstroms (Å), but separation in gases at normal temperature and pressure is of the order of 30 Å.

Solids exists in three forms—crystalline, polycrystalline, and amorphous. In crystalline materials, there is a regular arrangement of the constituent atoms or molecules; in polycrystalline, the substance exists as a cluster ...