Laue class
From Online Dictionary of Crystallography
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Revision as of 13:59, 26 March 2019 by ShigeruOhba (talk | contribs)
Classe de Laue (Fr). Laue-Klasse (Ge). Classi di Laue(It). ラウエ群(Ja). Clase de Laue (Sp).
Definition
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 1.6 of International Tables for Crystallography, Volume A, 6th edition
- Chapter 2.4 of International Tables for Crystallography, Volume D