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BiAl₂S₄

Tetragonal · space group P4/nnc (No. 126) · Pearson tP28

Symmetry elements and Wyckoff positions (interactive)

BiAl₂S₄ in P4/nnc

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

Unit cell

Lattice constants
a = 7.492 Å, b = 7.492 Å, c = 11.883 Å; α = 90.00°, β = 90.00°, γ = 90.00°
Cell volume
667.0 ų
Atoms in the conventional cell
28 (Al 8, Bi 4, S 16)
Formula units Z
4
Pearson symbol
tP28 — tetragonal, primitive lattice, 28 atoms per conventional cell
Symmetry operations
16 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
Al1Al4c40.25000.75000.7500
Al2Al4d40.25000.75000.0000
Bi3Bi4e40.25000.25000.1181
S4S16k160.08650.59240.1254

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 28 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

A2BC4_tP28_126_cd_e_k-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol tP28, then the space-group number 126, then the Wyckoff letters occupied by each element in turn (Al: 4c; Al: 4d; Bi: 4e; S: 16k). Two structures with the same label are the same arrangement with different cell parameters or coordinates.

Other compounds with this structure

BiAl₂Se₄, BiGa₂S₄, BiGa₂Se₄, Bi(Al, Ga)₂S₄, Bi(Al, Ga)₂Se₄ <!--beginning with an

Source

Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A2BC4_tP28_126_cd_e_k-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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