Question

Distance between tetrahedral and octahedral void in fcc lattice will be
(Given edge length of unit cell = a)

• A. $\frac{\sqrt{3}a}{4}$
• B. $\sqrt{3}a$
• C. $\sqrt{3}\frac{a}{2}$
• D. $\frac{\sqrt{3}a}{3}$

Answer 1

Answer: (A)

Octahedral void is found at centre of cube and edge centre while tetrahedral voids are present at 1/4th of the distance along each body diagonal.
$2\times$ distance between tetrahedral and octahedral voids $=\frac{\sqrt{3}a}{2}$
So distance between tetrahedral and octahedral void $=\frac{\sqrt{3}a}{4}$ .