Closest-Packing
GLY 4200
Lab 4 – Fall, 2014
1
Hexagonal Closest-Packing
(HCP)
• Third layer is directly over the first layer
• Repeat is ABABAB…
2
Cubic
ClosestPacking
(CCP)
• Third layer is distinct from the first two
layers
• Repeat is ABCABCABC….
3
Intralayer Voids
• Space between the
spheres, within the
layer, is a trigonal
planar void
• A void is a space
which may be
occupied by a small
ion, usually a cation
4
Void:Sphere Ratio
• Ratio of voids/spheres
• Around each sphere
there are six voids
• Around each void there
are three spheres
• The ratio of
voids/spheres is
therefore 2:1
5
Interlayer Voids
• Both types of packing have empty places
(voids) between layers
• There are two types of voids
• Each has a different CN
6
Assignment
• Find out what types of voids are present
• Find the ratio of voids/sphere for each type
• Find the ratio of the voids to one another
7