Laue class

From Online Dictionary of Crystallography

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Classes de Laue (Fr); Laue Klassen (Ge); Clases de Laue (Sp); Classi di Laue (It); ラウエ結晶類(Ja).


The Laue classes are eleven geometric crystal classes containing centrosymmetric crystallographic types of point groups and their subgroups. When absorption is negligible and Friedel's law applies, it is impossible to distinguish by diffraction between a centrosymmetric point group and one of its non-centrosymmetric subgroups; only point groups belonging to different Laue classes can then be distinguished.

Laue classes Non-centrosymmetric groups
in the same Laue class
[math]{\bar 1}[/math] 1
2/m 2, m
mmm 222, 2mm
[math]{\bar 3}[/math] 3
[math]{\bar 3}m[/math] 32, 3m
4/m 4, [math]{\bar 4}[/math]
4/mmm 422, [math]{\bar 4}2m[/math], 4mm
6/m 6, [math]{\bar 6}[/math]
6/mmm 622, [math]{\bar 6}2m[/math], 6mm
[math]m{\bar 3}[/math] 23
[math]m{\bar 3}m[/math] 432, [math]{\bar 4}[/math]32

See also

Chapter 3.1 of International Tables of Crystallography, Section A
Chapter 2.4 of International Tables of Crystallography, Section D