Question

In solid oxide ions form a cpp lattice, half of the tetrahedral vpids and octahederal voids occupied by b entities. determine the formula of the solid

Answer 1

CCP,atoms are arranged in corners and Face centred lattice,
and therefore total no of atoms in ccp=4
In ccp no. of tetrahedral voids=2xN,where N is the total No. Of atoms in ccp
Similarly,no. of octahedral Voids=N
Coming to your question,
No. of oxide ions=4 and therefore N=4
A=1/2 tetrahedral voids =1/2(2×4)=4
B=octahedral voids = N= 4
O= 4(forms CCP lattice )
Therefore formula is ABO