TYPES OF UNIT CELL / PRIMITIVE AND NON PRIMITIVE UNIT CELL

Types of unit cells :

Basically unit cglls are of two types

1) Primitive unit cells : (simple unit cells) 

ln these unit cells constituent particles like atoms, ions or molecules are present only at the comers of the unit cell.

2) Non-primitive unit cells (central unit cells)

In these unit cells constituent particles are present at the corners as well as at some other positions. They are further classilied into three types.

i) Face centred unit cell
ii) Body centred unit cell
iii) End centred unit cell

i) Face centred unit cell: In these unit cell the constituent particles are present at the corners as well as at the centre of each face.

ii) Body centred unit cell : In these unit cells the constituent particles are present at the corners as well as at the centre of the unit.

iii) End centred unit cell : In these unit cells constituent particles are present at the corners as well as at the centre of two opposite faces.