Question

If atom A is ideally fit in an octahedral void formed by atom B which crystallizes in fcc structure of radius 1.42 Å then what will be the minimum distance between centers of A and B (in Å)? (Use $\sqrt{2}=1.41$)

Answer 1

Distance between centers of A and B is half of edge length i.e.
$\frac{a}{2}=\sqrt{2}r=\sqrt{2}\times 1.42\AA =2.0022\AA$