Classifications of solids

CLASSIFICATIONS OF SOLIDS

From the point of view of crystal structure, materials can be broadly classified into :

1. Crystalline, and

2. Non-crystalline or Amorphous.

1. Crystalline Materials

✓ The materials in which the atoms are arranged in some regular repetition pattern are called the crystalline materials.

✓ A crystalline material can be either monocrystal or polycrystalline. A single crystal consists of only one crystal, whereas the polycrystalline material consists of many crystals separated by well defined boundaries.

✓ Examples: The vast majority engineering materials, for instance all metals, many ceramics and most minerals are crystalline.

2. Non-crystalline or Amorphous Materials

✓ In this type of materials, the atoms or molecules are arranged in an irregular fashion. It is not based on a regular repetition pattern.

✓ The modern view is that the amorphous materials are supercooled liquids having a very high viscosity.

✓ Examples: Glass, rubber and polymers.