In a normal spinel type structure, the oxide ions are arranged in ccp whereas 18 tetrahedral holes are occupied by Zn2+ ions and 50% of octahedral holes are occupied by Fe3+ ions. The formula of the compound is ?
Zn2Fe2O4
Number of O - atoms per unit cell =18×8+12×6=4
Number of octahedral holes per unit cell =1×4=4
Number of Fe3+ ions per unit cell =50×4100=2
Number of Zn2+ ions per unit cell =18×8=1
Hence, formula : ZnFe2O4