Question

In an FCC unit cell, a cube is formed by joining the centres of all the tetrahedral voids to generate a new cube. Then the new cube would contain voids as:

• A. 1 full Tetrahedral void, 1 full Octahedral void
• B. 1 full Tetrahedral void only
• C. 8 full Tetrahedral voids and 1 full Octahedral void
• D. 1 full Octahedral void onlt

Answer 1

The correct option is A 1 full Tetrahedral void, 1 full Octahedral void

New, tetrahedral voids will be at corners of the cube .

Effective number of tetrahedral voids $=8\times \frac{1}{8}=1$

Octahedral void will be at body center.

Total octahedral voids $=1$