Question

The coordination number of $Z{n}^{2+}$ and $S^{2-}$ ions in the zinc blende $\left(ZnS\right)$ type structure is

• A. 4 : 4
• B. 6 : 6
• C. 8 : 8
• D. 4 : 8

Answer 1

The correct option is A 4 : 4

In Zinc blende,
$S^{2-}$ ions forms the fcc lattice. Thus, it occupies the corners and face centre of the cubic unit cell.
Thus lattice form has 8 tetrahedral voids and 4 octahedral void for an unit cell.
$Z{n}^{2+}$ ion occupy only alternate (non adjacent) four tetrahedral void.
Each $Z{n}^{2+}$ in terahedral void is surrounded tetrahedrally by four $S^{2-}$ ions.
Each $S^{2-}$ ion is surrounded tetrahedrally by four $Z{n}^{2+}$ ions.
Thus, the coordination number of $ZnS$ is 4 : 4