Let number of octahedral holes in the lattice
=x ∴ Number of tetrahedral holes in the lattice
=2x ( ∵ Number of tetrahedral holes
=2× number of octahedral holes)
Now,
A+ ions occupy
25% of tetrahedral holes. Hence, number of tetrahedral holes occupied in the lattice
=2x×25%=2x×= since, number of octahedral holes = Number of lattice points.
∴ Number of octahedral holes
=x ∴ Molecular formula of the crystal is
Ax/2Bx or
AB2