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Crystal Lab › Prototype structures › Tetragonal

TlZn₂Sb₂

Tetragonal · space group I4 (No. 79) · Pearson tI20

Symmetry elements and Wyckoff positions (interactive)

TlZn₂Sb₂ in I4

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

Unit cell

Lattice constants
a = 8.649 Å, b = 8.649 Å, c = 7.287 Å; α = 90.00°, β = 90.00°, γ = 90.00°
Cell volume
545.1 ų
Atoms in the conventional cell
20 (Tl 4, Sb 8, Zn 8)
Formula units Z
4
Pearson symbol
tI20 — tetragonal, body-centred lattice, 20 atoms per conventional cell
Symmetry operations
8 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
Tl2Tl2a20.00000.00000.0000
Tl3Tl2a20.00000.00000.5104
Sb1Sb8c80.16400.66300.7804
Zn4Zn8c80.13300.36500.9144

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 20 atoms drawn above are these sites multiplied by all 8 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

A2BC2_tI20_79_c_2a_c-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol tI20, then the space-group number 79, then the Wyckoff letters occupied by each element in turn (Tl: 2a; Tl: 2a; Sb: 8c; Zn: 8c). 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 A2BC2_tI20_79_c_2a_c-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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