Zinc Sulphide (ZnS) Structure

ZINC SULPHIDE (ZnS) STRUCTURE

Zinc sulphide structure is also known as the Zinc blende structure. This structure is identical to diamond structure except that two interpenetrating FCC sub- lattices are of different atoms one composed entirely of zinc atoms and the other entirely of sulphur atoms. (fig. 1.29).

This is therefore true face-centered cubic structure with a basis of two different atoms.

Formation of structure

We know the diamond structure is made by carbon atoms [corner + face centred +4 atoms inside the unit cell].

In the diamond structure if the corner and face centred atoms are replaced by sulphur (S^-) atoms and four atoms present inside the unit cell are replaced by the zinc (Zn⁺) atoms, then we get zinc sulphide structure. It is shown as in fig. 1.29. It also has the coordination number as 4.

Example

Many important compounds such as AlAs, GaAs, GaP, GaSb, InAs, InP, InSb, ZnS, ZnSe, Cds, CuCl etc. have this type of structure.

Density of Crystal

This is defined as:

Density of the crystal (p) = Mass of unit cell / Volume of unit cell

Mass of unit cell = (Atomic mass / Avogadro number) × Number of atoms per unit cell

= (M/N_A) x n

n → number of atoms per unit cell and

N_A → Avogadro's number,

M → the atomic weight and

a → side of a cubic unit cell