The structure of a mixed oxide is cubic closed packed (ccp). The cubic unit cell of mixed oxide is composed of oxide ions. One fourth of the tetrahedral voids are occupied by divalent mtal A and the octahedral voids are occupied by a monovalent metal B. The formula of the oxide is:
1)in a cubic close packing, the number of octahedral voids is equal to number of atoms and number of tetrahedral voids is equal to the twice the number of atoms.
Number of atoms in a ccp array = 1