Electron microscopy
 
I4/mcm (140) Space Group
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Table 1875. I4/mcm (140) space group.

Name in the International Tables for Crystallography
I4/mcm I
139 4/mmm
Crystal system
Tetragonal 4/mmm
Asymm
0 ≤ x ≤ 1/2 and 0 ≤ y ≤ 1/2 and 0 ≤ z ≤ 1/4 and y ≤ 1/2-x
32 Extinction conditions k = 2n and l = 2n for 0 k l reflections (same as I-4c2 and I4cm).
Symmetry (atomic coordinates)
X, Y, Z; -X, -Y, Z; -Y, X, Z; Y, -X, Z; -X, Y, 1/2-Z; X, -Y, 1/2-Z; Y, X, 1/2-Z; -Y, -X, 1/2-Z; -X, -Y, -Z; X, Y, -Z; Y, -X, -Z; -Y, X, -Z; X, -Y, 1/2+Z; -X, Y, 1/2+Z; -Y, -X, 1/2+Z; Y, X, 1/2+Z; 1/2+X, 1/2+Y, 1/2+Z; 1/2-X, 1/2-Y, 1/2+Z; 1/2-Y, 1/2+X, 1/2+Z; 1/2+Y, 1/2-X, 1/2+Z; 1/2-X, 1/2+Y, -Z; 1/2+X, 1/2-Y, -Z; 1/2+Y, 1/2+X, -Z; 1/2-Y, 1/2-X, -Z; 1/2-X, 1/2-Y, 1/2-Z; 1/2+X, 1/2+Y, 1/2-Z; 1/2+Y, 1/2-X, 1/2-Z; 1/2-Y, 1/2+X, 1/2-Z; 1/2+X, 1/2-Y, Z; 1/2-X, 1/2+Y, Z; 1/2-Y, 1/2-X, Z; 1/2+Y, 1/2+X, Z
Other characteristics
For distorted perovskite structures, the adjacent octahedra along the c-axes are rotated in antiphase manner.
Crystal examples
SrTiO3 (a = 5.513 Å and c = 7.807 Å):: Sr (4b): (0, 0.5, 0.25), Ti (4c): (0, 0, 0), O (4a): (0, 0, 0.25), and O (8h): (u, u+0.5, 0)
CaTiO3, CeAlO3, CeVO3, CaCsCl3, KMnF3, LaVO3, RbAgF3, SrTiO3, SrZrO3, La0.75Sm0.25VO3, SrMn0.5Sb0.5O3, SrMn0.5Sb0.5O3

 

 

 

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