Electron microscopy
  
P6/mmm (191) Space Group
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Table 1877. P6/mmm (191) space group.

Name in the International Tables for Crystallography
 P6/mmm
Lattice type
 P
Patterson space group
 191
Point group
 6/mmm
Crystal system
 Hexagonal
Laue class
 6/mmm
Asymm
 0 ≤ x ≤ 2/3 and 0 ≤ y ≤ 1/3 and 0 ≤ z ≤ 1/2 and x ≤ (1+y)/2 and y ≤ x/2
Number of symmetry operators
 24
Symmetry (atomic coordinates)
X, Y, Z; -Y, X-Y, Z; Y-X, -X, Z; -X, -Y, Z; Y, Y-X, Z; X-Y, X, Z; Y, X, -Z; X-Y, -Y, -Z; -X, Y-X, -Z; -Y, -X, -Z; Y-X, Y, -Z; X, X-Y, -Z; -X, -Y, -Z; Y, Y-X, -Z; X-Y, X, -Z; X, Y, -Z; Y-X, -X, -Z; -Y, X-Y, -Z; -Y, -X, Z; Y-X, Y, Z; X, X-Y, Z; Y, X, Z; X-Y, -Y, Z; -X, Y-X, Z
Characteristics of similar space groups
 P622, P6mm, P6m2, and P6/mmm: hexagonal, no glide planes or screw axes.
Conditions for kinematically-allowed reflections
 No conditions
Crystal examples
 T1 (Al2CuLi): a = 0.497 nm and c = 0.93 nm [1]
 

 

 

 

 

 

 

[1] Kenneth S. Vecchio and David B. WILLIAMS, Convergent Beam Electron Diffraction Analysis of the T1 (Al2CuLi) Phase in Al-Li-Cu Alloys, Metallurgical Transactions A, 19A, 1988-2885, (1988).

 

 

 
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