Question

If Z is the number of atoms in the unit cell that represents the closed packing sequence ABCABC, then the number of tetrahedral voids in the unit cell is equal to :

• A. Z
• B. 2Z
• C. $\frac{Z}{2}$
• D. $\frac{Z}{4}$

Answer 1

The correct option is B 2Z

Since closed packing sequence is ABCABC. Thus it is 3D close packing sequence.

In 3D close packing, there are $2$ tetrahedral voids per atom. So, number of tetrahedral voids is $2Z$.