ELCT780 HW3 : Structure and X-ray Diffraction
(will count as 2 homeworks)
1. Carry out the exercises in the bravais simulation handout and summarize your
findings in a concise 2 page report. You may work together to get the answers,
but the report should be individual. Notice that the reciprocal lattice for the
hexagon is rotated with respect to the real space lattice. Why? Address this point
in your report. (100pts)
2. For an ideal tetrahedral bond calculate the bond-angle. Show all your work. (20
pts)
3. For an ideal hexagonal close packed structure, calculate the c/a ratio, where c is
the lattice spacing in the c-direction (001) and a is the lattice constant in the adirection(100). Show all your work. (20pts)
4. From the KCl x-ray spectrum given in Kittel Ch.2, calculate the spacings of each
indexed set of planes. What is the lattice constant? (30)
5. What is the structure factor for graphite? Start with the graphene unit cell, as
you did in 1, and then do AB stacking to get the graphite lattice. The B position is
in the center of the hexagon. Use Cartesian co-ordinates to get the vectors in
(x,y,z) form. You may use fC as the carbon atomic form factor. (30 points).