# Unit cell volume

1. Nov 17, 2009

### ming2194

1. The problem statement, all variables and given/known data
Q 2.

(a) For the HCP crystal structure, show that the ideal c/a ratio is 1.633. (10%)

(b) Hence, calculate the unit cell volume of cadmium with a HCP structure and atomic radius of
0.1490 nm. Assume that the lattice period is equal to two times of the atomic radius. (5%)

2. Relevant equations

3. The attempt at a solution
(a) part is okay.
For (b) part, may i use the eqution Vc=6(R^2)C(3^1/2) without proving?
or are there any other methods to find Vc by using the data c/a=1.633? (i know the eqution p=nA/(Vc)(Na) but seems not related to a=2R/1.6333)