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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

Setting
Loading the group…
x = 0.10, y = 0.17, z = 0.08

Unit 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

SiteElementWyckoffMultiplicityxyz
Al1Al2a20.00000.00000.0000
Cu4Cu2c20.00000.00000.5000
Al2Al4i40.30200.00000.9570
Al3Al4i40.60500.00000.4870
Cu5Cu4i40.98400.00000.7400
Cu6Cu4i40.66300.00000.2720

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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