Structure of Materials An Introduction to Crystallography, Diffraction and Symmetry

In this chapter, we begin the process that will take up the remainder of this book, of describing about 100 important crystal structures. Since metallic structures form an important class of structures, with many practical applications, we will take this and the following chapter to introduce a few basic and a long list of derived structures. We begin with a brief description of the most important parent structures and introduce the Hume–Rothery rules and some basic phase diagrams. Then we cover a more systematic approach to the description of derivative and superlattice structures in fcc, bcc, diamond, and hcp-derived structures. We conclude the chapter with a discussion of structures with interstitial alloys, alternative stacking sequences, and natural and artificial (commensurate and incommensurate) long-period superlattices, including how they can be identified using X-ray diffraction methods.

Introductory comments

It is often useful to go beyond the description of a crystal in terms of the Bravais lattice and the unit cell decoration. In this chapter, we examine ways to disassemble and understand a crystal structure in terms of:

1. • Derivative structures: New structures can often be derived from simpler structures by substitutions of one atom for another.

2. • Interstitial structures: New structures can result from the ordered occupation of subsets of the interstitial sites in simple structures.

3. […]