Crystal Lab › Prototype structures › Tetragonal
BiAl₂S₄
Tetragonal · space group P4/nnc (No. 126) · Pearson tP28
Symmetry elements and Wyckoff positions (interactive)
BiAl₂S₄ in P4/nnc
SettingUnit 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
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Al1 | Al | 4c | 4 | 0.2500 | 0.7500 | 0.7500 |
| Al2 | Al | 4d | 4 | 0.2500 | 0.7500 | 0.0000 |
| Bi3 | Bi | 4e | 4 | 0.2500 | 0.2500 | 0.1181 |
| S4 | S | 16k | 16 | 0.0865 | 0.5924 | 0.1254 |
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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