Crystal Structure

Physics SSS1 Second Term

WEEK 10

Crystal Structure

Performance Objectives

Students should be able to:

1. Examine the arrangement of atoms in the crystal structure
2. Distinguish between crystalline and amorphous substances

Content

Crystal structure

In a crystal, atoms are arranged in straight rows in a three-dimensional periodic pattern. A small part of the crystal that can be repeated to form the entire crystal is called a unit cell.

Asymmetric     unit

Primitive     unit cell

Conventional     unit cell

Crystal

A crystal can be specified in several ways. One way is to repeat the primitive unit cell at each translation vector,

T⃗ =ha⃗ 1+ka⃗ 2+la⃗ 3T→=ha→1+ka→…