Difference between revisions of "Laue class"

From Online Dictionary of Crystallography

(class is 類。群 is group. Here we speak about classes, not groups.)
(typo corrected)
Line 32: Line 32:
|<math>m{\bar 3}</math>|| 23
|<math>m{\bar 3}</math>|| 23
|<math>m{\bar 3}m</math>|| 432, <math>{\bar 4}</math>32
|<math>m{\bar 3}m</math>|| 432, <math>{\bar 4}</math>3''m''

Latest revision as of 11:20, 7 October 2019

Classe de Laue (Fr). Laue-Klasse (Ge). Classi di Laue(It). ラウエ結晶類(Ja). Clase de Laue (Sp).


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]3m

See also

  • Chapter 1.6 of International Tables for Crystallography, Volume A, 6th edition
  • Chapter 2.4 of International Tables for Crystallography, Volume D