In a face centred cubic arrangement of metallic atoms, what is the relative ratio of the sizes of tetrahedral and octahedral voids ?
(A). Consider one tetrahedral void. If the side length of the tetrahedron is l and if d is the distance from the centre to the corner, then
but if a is the side length of the unit cell
and , where is the radius of the corner atom and the radius of the void.
For the octahedral void, if the radius of the void is , then
ratio of the sizes of tetrahedral to octahedral voids