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

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Closest-Packing GLY 4200 Lab 4 – Fall, 2012

Hexagonal Closest-Packing (HCP) Source: http://wps.prenhall.com/wps/media/objects/602/616516/Media_Assets/Chapter10/Text_Images/FG10_21UN.JPG Third layer is directly over the first layer Repeat is ABABAB…

Cubic Closest-Packing (CCP) http://wps.prenhall.com/wps/media/objects/602/616516/Media_Assets/Chapter10/Text_Images/FG10_21UN.JPG Third layer is distinct from the first two layers Repeat is ABCABCABC….

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: http://uwp.edu/~li/geol200-01/cryschem/

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

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

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