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Crystal Lab › Prototype structures › Trigonal

Rhombohedral CuTi₂S₄ CuS₄Ti₂

Trigonal · space group R-3m (No. 166) · Pearson hR28

Symmetry elements and Wyckoff positions (interactive)

Rhombohedral CuTi₂S₄ in R-3m

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

Unit cell

Lattice constants
a = 7.024 Å, b = 7.024 Å, c = 34.834 Å; α = 90.00°, β = 90.00°, γ = 120.00°
Cell volume
1488.4 ų
Atoms in the conventional cell
84 (Ti 24, Cu 12, S 48)
Formula units Z
12
Pearson symbol
hR28 — hexagonal / trigonal, rhombohedral lattice, 28 atoms per conventional cell
Symmetry operations
36 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
Ti7Ti3a30.00000.00000.0000
Ti8Ti3b30.00000.00000.5000
Cu1Cu6c60.00000.00000.1876
Cu2Cu6c60.00000.00000.3545
S3S6c60.00000.00000.1232
S4S6c60.00000.00000.2889
S5S18h180.82370.17630.3757
S6S18h180.16020.83980.4544
Ti9Ti18h180.50450.49550.5810

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 84 atoms drawn above are these sites multiplied by all 36 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

AB4C2_hR28_166_2c_2c2h_abh-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol hR28, then the space-group number 166, then the Wyckoff letters occupied by each element in turn (Ti: 3a; Ti: 3b; Cu: 6c; Cu: 6c; S: 6c; S: 6c; S: 18h; S: 18h; Ti: 18h). Two structures with the same label are the same arrangement with different cell parameters or coordinates.

Note: Rhombohedral.

Source

Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry AB4C2_hR28_166_2c_2c2h_abh-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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