Primitive Unit Cells
If the constituent particles of a crystal lattice are present only on the corner positions of a unit cell, it is known as primitive unit cell.
Centered Unit Cells
- If the constituent particles of a crystal lattice are present at positions other than corners in addition to those at corners, it is known as centered unit cell.
- Centered unit cells are of three types:
- Body-Centred Unit Cells:
If the constituent particles of a unit cell are present at its body-centre besides the ones that are at its corners.
- Face-Centred Unit Cells:
If the constituent particles of a unit cell are present at the center of each face, besides the ones that are at its corners.
- End-Centred Unit Cells:
If the constituent particles of a unit cell are present the center of any two opposite faces besides the ones present at its corners.
