Difference between revisions of "Laue class"
From Online Dictionary of Crystallography
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(class is 類。群 is group. Here we speak about classes, not groups.) |
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| − | <font color="blue">Classe de Laue</font> (''Fr''). <font color="red">Laue-Klasse</font> (''Ge''). <font color="black">Classi di Laue</font>(''It''). <font color="purple"> | + | <font color="blue">Classe de Laue</font> (''Fr''). <font color="red">Laue-Klasse</font> (''Ge''). <font color="black">Classi di Laue</font>(''It''). <font color="purple">ラウエ結晶類</font>(''Ja''). <font color="green">Clase de Laue</font> (''Sp''). |
Revision as of 08:52, 27 March 2019
Classe de Laue (Fr). Laue-Klasse (Ge). Classi di Laue(It). ラウエ結晶類(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