Crystal Lab › Prototype structures › Orthorhombic
Cr₄AlB₆
Orthorhombic · space group Cmmm (No. 65) · Pearson oC22
Symmetry elements and Wyckoff positions (interactive)
Cr₄AlB₆ in Cmmm
SettingUnit cell
- Lattice constants
- a = 21.280 Å, b = 2.952 Å, c = 3.013 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 189.3 ų
- Atoms in the conventional cell
- 22 (Al 2, B 12, Cr 8)
- Formula units Z
- 2
- Pearson symbol
- oC22 — orthorhombic, base-centred lattice, 22 atoms per conventional cell
- Symmetry operations
- 16 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Al1 | Al | 2a | 2 | 0.0000 | 0.0000 | 0.0000 |
| B2 | B | 4g | 4 | 0.1050 | 0.0000 | 0.0000 |
| B3 | B | 4g | 4 | 0.6481 | 0.0000 | 0.0000 |
| B4 | B | 4g | 4 | 0.7298 | 0.0000 | 0.0000 |
| Cr5 | Cr | 4h | 4 | 0.5763 | 0.0000 | 0.5000 |
| Cr6 | Cr | 4h | 4 | 0.1884 | 0.0000 | 0.5000 |
The multiplicity and the Wyckoff letter say how many copies of the site the group makes in one cell and on which kind of symmetry element the site sits; the 22 atoms drawn above are these sites multiplied by all 16 operations. Press Wyckoff under Colour to see the sites, and tick a symmetry element on the left to see which atoms lie on it.
How to read the label
AB6C4_oC22_65_a_3g_2h-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oC22, then the space-group number 65, then the Wyckoff letters occupied by each element in turn (Al: 2a; B: 4g; B: 4g; B: 4g; Cr: 4h; Cr: 4h). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry AB6C4_oC22_65_a_3g_2h-001 (M. J. Mehl et al., Comput. Mater. Sci. 136, S1 (2017); D. Hicks et al., ibid. 161, S1 (2019) and 199, 110450 (2021); S. Eckert et al., ibid. 240, 112988 (2024)). Symmetry elements, Wyckoff assignment and the diagram are computed on this page from the group operations.
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