Question

Right option for the number of tetrahedral and octahedral voids in hexagonal primitive unit cell are:

• A. 8,4
• B. 6,12
• C. 2,1
• D. 12,6

Answer 1

Answer: (D)

A hexagonal primitive unit cell contains 6 atoms in the crystal structure i.e. n = 6
We know that, for hcp,

The number of octahedral voids will be equal to the number of atoms in the crystal structure.
No. of octahedral voids = 6.

The number of tetrahedral voids will be equal to two times the number of atoms in the crystal structure .
No. of tetrahedral voids = 2 x 6 = 12.