Starting with the cubic close packing of oxygen ions a How m

Starting with the cubic close packing of oxygen ions: a) How many tetrahedral and how many octahedral sites are there per unit cell? b) What is the ratio of octahedral sites to oxygen ions? What is the ratio of tetrahedral sites to oxygen ions? c) What oxide would you get if half octahedral sites are filled, 2/3, and all.

Solution

(a) 8 tetrahedral and 4 octahedral

(b) Octahedral sites to oxygen ions = 1:1;

tetrahedral sites to oxygen ions = 2:1

(c) 1/2 filled = MO₂;

2/3 filled = M₂O₃;

and all filled = MO