Element B' forms ccp structure and 'A' occupies half of the octahedral voids, while oxygen atoms occupy all the tetrahedral voids. The structure of bimetallic oxide is:
Number of atoms per unit cell in ccp = N =4
Number of octahedral voids = N =4
A occupies half of the octahedral voids, thus A atoms per unit cell = 4/2 =2
Tetrahedral voids = 2 × N =8
So number of oxygen atoms = 8
A:B:0:: 2:4:8
Thus, structure of bimetallic oxide is AB2O4 .