Lattice Parameters of the Unit Cell

LATTICE PARAMETERS OF THE UNIT CELL

The unit cell is constructed if the distance between two neighbouring lattice points along three directions and angles between them are known.

The distance between two neighbouring lattice points is the edge of the unit cell. The lengths OA, OB, OC in three axes OX, OY and OZ are the axial lengths or intercepts. (Fig. 1.8)

In fig 1.8, the axial lengths OA = a, OB = b and OC = c are known as intercepts a, b and c along three axes.

Interfacial angles

The angles between three intercepts (α, β and γ) are called interfacial angles.

The three intercepts and three interfacial angles are the lattice parameters of the unit cell. They determine the actual size and shape of the unit cell:

(a, b, c) – axial lengths, (α, β, γ) - interfacial angles.