Crystal Structure

Materials are categorized into 2, based on the arrangement of atoms or molecules.

• Crystalline
• Amorphous

Crystalline

When atoms or molecules are arranged in a ordered structure. Long-order is present.

• Situated in a repeating array over large atomic distances (long-range order).
• Example: Metals and Ceramics.

Atomic arrangement is usually described by space lattice.

Amorphous (or Non Crystalline)

When atoms or molecules are randomly arranged. Long-range order is absent.

• Example: Glass.
• Polymers are semi-crystalline.