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Sn₄As₃

Trigonal · space group R3m (No. 160) · Pearson hR7

Symmetry elements and Wyckoff positions (interactive)

Sn₄As₃ in R3m

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

Unit cell

Lattice constants
a = 4.089 Å, b = 4.089 Å, c = 36.059 Å; α = 90.00°, β = 90.00°, γ = 120.00°
Cell volume
522.1 ų
Atoms in the conventional cell
21 (As 9, Sn 12)
Formula units Z
3
Pearson symbol
hR7 — hexagonal / trigonal, rhombohedral lattice, 7 atoms per conventional cell
Symmetry operations
18 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
As1As3a30.00000.00000.5724
As2As3a30.00000.00000.0027
As3As3a30.00000.00000.4323
Sn4Sn3a30.00000.00000.2907
Sn5Sn3a30.00000.00000.7131
Sn6Sn3a30.00000.00000.1378
Sn7Sn3a30.00000.00000.8660

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 21 atoms drawn above are these sites multiplied by all 18 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

A3B4_hR7_160_3a_4a-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol hR7, then the space-group number 160, then the Wyckoff letters occupied by each element in turn (As: 3a; As: 3a; As: 3a; Sn: 3a; Sn: 3a; Sn: 3a; Sn: 3a). 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 A3B4_hR7_160_3a_4a-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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