Crystal Viewer

This Demonstration gives insight into the crystal symmetries of five standard crystal symmetries of pure elements. These lattice symmetries are

1) simple cubic SC (e.g., polonium);

2) face-centered cubic FCC (e.g., copper);

3) body-centered cubic BCC (e.g., iron);

4) hexagonal closed-packed HCP (e.g., helium);

5) diamond DIA (e.g., silicon).

The direction (h,k,l) defines a plane to which this direction is perpendicular. This plane is called the crystal plane (h,k,l). The three values h, k, and l are often referred to as Miller indices.

THINGS TO TRY

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DETAILS

The viewer not only allows studying the symmetry of specific planes, but also visualizes the density of the atoms in certain directions. This is important for a process called channeling (see the Wikipedia entry). In this case a (high-energy) atom or ion penetrates the crystal. If the atoms of the crystal have a low density in the direction of penetration, the penetration depth is probably high, and vice versa. One may say that in low-density directions channels open for the penetrating particle. Usually, these channels open in high-symmetry crystal directions. To visualize the effect of different cross sections, it is possible to change the size.

References:

For more structures that appear in crystals of pure elements see N. W. Ashcroft and N. D. Mermin, Solid State Physics, Philadelphia: Sounders College Publishing, 1976.

C. Kittel, Introduction to Solid State Physics, 7th ed., New York: John Wiley & Sons, Inc., 1996.

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Contributed by: Nikolai Mikuszeit

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