Crystal Lab › Prototype structures › Orthorhombic
MoAlB
Orthorhombic · space group Cmcm (No. 63) · Pearson oC12
Symmetry elements and Wyckoff positions (interactive)
MoAlB in Cmcm
SettingUnit cell
- Lattice constants
- a = 3.199 Å, b = 13.922 Å, c = 3.094 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 137.8 ų
- Atoms in the conventional cell
- 12 (Al 4, B 4, Mo 4)
- Formula units Z
- 4
- Pearson symbol
- oC12 — orthorhombic, base-centred lattice, 12 atoms per conventional cell
- Symmetry operations
- 16 per cell
- Calculated density
- 6.45 g cm⁻³ (cell contents ÷ cell volume, standard atomic weights)
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Al1 | Al | 4c | 4 | 0.0000 | 0.1985 | 0.2500 |
| B2 | B | 4c | 4 | 0.0000 | 0.0338 | 0.2500 |
| Mo3 | Mo | 4c | 4 | 0.0000 | 0.4105 | 0.2500 |
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 12 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
ABC_oC12_63_c_c_c-005: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oC12, then the space-group number 63, then the Wyckoff letters occupied by each element in turn (Al: 4c; B: 4c; Mo: 4c). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Other compounds with this structure
NbNiB, MgNiTb, WAlB
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry ABC_oC12_63_c_c_c-005 (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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