Crystal Lab › Prototype structures › Monoclinic
CuAl
Monoclinic · space group C12/m1 (No. 12) · Pearson mC20
Symmetry elements and Wyckoff positions (interactive)
CuAl in C12/m1
SettingUnit cell
- Lattice constants
- a = 12.060 Å, b = 4.105 Å, c = 9.884 Å; α = 90.00°, β = 145.03°, γ = 90.00°
- Cell volume
- 280.5 ų
- Atoms in the conventional cell
- 20 (Al 10, Cu 10)
- Formula units Z
- 10
- Pearson symbol
- mC20 — monoclinic, base-centred lattice, 20 atoms per conventional cell
- Symmetry operations
- 8 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Al1 | Al | 2a | 2 | 0.0000 | 0.0000 | 0.0000 |
| Cu4 | Cu | 2c | 2 | 0.0000 | 0.0000 | 0.5000 |
| Al2 | Al | 4i | 4 | 0.3020 | 0.0000 | 0.9570 |
| Al3 | Al | 4i | 4 | 0.6050 | 0.0000 | 0.4870 |
| Cu5 | Cu | 4i | 4 | 0.9840 | 0.0000 | 0.7400 |
| Cu6 | Cu | 4i | 4 | 0.6630 | 0.0000 | 0.2720 |
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 20 atoms drawn above are these sites multiplied by all 8 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
AB_mC20_12_a2i_c2i-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol mC20, then the space-group number 12, then the Wyckoff letters occupied by each element in turn (Al: 2a; Cu: 2c; Al: 4i; Al: 4i; Cu: 4i; Cu: 4i). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Other compounds with this structure
InPt, Cu₁₁In₉ <!--beginning with an
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry AB_mC20_12_a2i_c2i-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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