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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

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

Unit 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

SiteElementWyckoffMultiplicityxyz
Ca1Ca2a20.25000.25000.0000
Sr5Sr2b20.25000.25000.5000
Fe3Fe2c20.75000.25000.0000
Fe2Fe2d20.75000.25000.5000
S4S8m80.40900.59100.7500

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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