Construct the two point group diagrams for point group 32. (45 secs)

1

• Construct the two point group diagrams for point
  group 32. (45 secs)
• symmetry elements equivalent points
• CaF2 is Fm3m, a 5.462 Å, Ca in 4 a,
• F in 8c. Make a drawing of the crystal
• structure projected down 001
• The F atoms have how many Ca nearest
• neighbors (i.e., how many Ca atoms
• touch each F atom)?
• Since a 5.462 Å, what is the Ca-F
• bond distance? (A simple geometry
• calculation.)
• (9 mins)

2

• Metals with the ccp and hcp structures are both
  close packed.
• How are they different? Explain you must use
  drawings in your discussion. (2 mins)
• 4. For characteristic x-radiation, why is ?K? gt
  ?K?? (1 min)

3

• Construct the two point group diagrams for point
  group 6mm. (45 secs)
• symmetry elements equivalent points
• PtO2 is Pnnm, a 4.533, b 4.488, c 3.138 Å,
  Pt in 2a,
• O in 4g, x 0.652, y 0.281. Make a drawing
  of the crystal
• structure projected down 001. See list of
  equipoints on next slide.
• What is the coordination number for the Pt atoms
  (i.e., how many O atoms touch each Pt atom)?
• What is the shape of the Pt coordination
  polyhedron.
• (4 mins)

4
2.
5

• a. Are rutile and anatase polytypes?____
• b. Are rutile and anatase polymorphs?____
• c. Discuss how (in what way) the crystal
  structures of
• rutile and anatase are different.
• (1 min)
• A monoclinic crystal has a 6, b 4, c 10 Å,
  ? 110. Draw the k 0 level of the reciprocal
  lattice. You will have to estimate (guess) what
  the distances and angles are on your drawing.
  Show (mark) the reciprocal lattice vectors and
  angle for the reciprocal lattice unit cell.
• (2 min)