Fe is a BCC metal at lower temperatures and an FCC metal above 1184K, and approximately corresponds
to its Curie magnetic transition. Assume that the atomic radius of Fe is 0.15 nm for both phases, and
that there is no thermal expansion.
a) What is the lattice constant $a$ for FCC and BCC Fe (10 points)
b) For both FCC and BCC Fe, list the first four observed (structure factor $\neq$ 0) $d_{hkl}$ for FCC
and BCC Fe, where $d$ is the distance between the planes. Include the hkl values for each
of the observed planes for both FCC and for BCC (16 points---8 points for identifying the
hkl values for the first 4 observed planes, 8 points for writing the correct distances).
c) Using a Cu K-alpha source ($\lambda$=0.154 nm), write the 2$\theta$ values corresponding to the first
four observed peaks for FCC iron (4 points).
