3.091 Crystal Structures: Packing

This page illustrates the crystal structures most studied in 3.091.

The VRML models show the atoms as hard-spheres in contact (the Java applets currently do not).

Two key points to study:

1. Compare the close-packed structures of fcc and hcp (hexagonal close-packed)
2. Note how the diamond cubic and hcp are obtained from the fcc and hexagonal bravais lattices, respectively.

Simple Cubic

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VRML Simple Cubic

Body Centered Cubic

Face Centered Cubic

Diamond Cubic

"diamond cubic" is face centered cubic with a basis of two atoms per lattice site.

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VRML Diamond Cubic

Hexagonal

Hexagonal Close-Packed

"hexagonal close-packed" is the hexagonal lattice with a basis of two atoms per lattice site.

Compare this structure with the fcc structure above.

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VRML Hexagonal Close-Packed

Last modified: Wed Oct 23 17:47:42 1996