Crystal Lab › Prototype structures › Tetragonal
SrFe₂S₄
Tetragonal · space group P4/nbm (No. 125) · Pearson tP16
Symmetry elements and Wyckoff positions (interactive)
SrFe₂S₄ in P4/nbm
SettingUnit cell
- Lattice constants
- a = 7.910 Å, b = 7.910 Å, c = 5.500 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 344.1 ų
- Atoms in the conventional cell
- 16 (Ca 2, Sr 2, Fe 4, S 8)
- Formula units Z
- 2
- Pearson symbol
- tP16 — tetragonal, primitive lattice, 16 atoms per conventional cell
- Symmetry operations
- 16 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Ca1 | Ca | 2a | 2 | 0.2500 | 0.2500 | 0.0000 |
| Sr5 | Sr | 2b | 2 | 0.2500 | 0.2500 | 0.5000 |
| Fe3 | Fe | 2c | 2 | 0.7500 | 0.2500 | 0.0000 |
| Fe2 | Fe | 2d | 2 | 0.7500 | 0.2500 | 0.5000 |
| S4 | S | 8m | 8 | 0.4090 | 0.5910 | 0.7500 |
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 16 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
AB2C4D_tP16_125_a_cd_m_b-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol tP16, then the space-group number 125, then the Wyckoff letters occupied by each element in turn (Ca: 2a; Sr: 2b; Fe: 2c; Fe: 2d; S: 8m). 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 AB2C4D_tP16_125_a_cd_m_b-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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