1. Closest-Packing
GLY 4200
Lab 4 – Fall, 2012

2. Hexagonal Closest-Packing (HCP)
Source:
Third layer is directly over the first layer
Repeat is ABABAB…

3. Cubic Closest-Packing (CCP)
Third layer is distinct from the first two layers
Repeat is ABCABCABC….

4. 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
Source:

5. 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

6. Interlayer Voids
Both types of packing have empty places (voids) between layers
There are two types of voids
Each has a different CN

7. Assignment Find our what types of voids are present
Find the ratio of voids/sphere for each type
Find the ratio of the voids to one another