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Crystal Lab › Prototype structures › Tetragonal

ThCr₂Si₂

Tetragonal · space group I4/mmm (No. 139) · Pearson tI10

Symmetry elements and Wyckoff positions (interactive)

ThCr₂Si₂ in I4/mmm

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

Unit cell

Lattice constants
a = 4.043 Å, b = 4.043 Å, c = 10.577 Å; α = 90.00°, β = 90.00°, γ = 90.00°
Cell volume
172.9 ų
Atoms in the conventional cell
10 (Th 2, Cr 4, Si 4)
Formula units Z
2
Pearson symbol
tI10 — tetragonal, body-centred lattice, 10 atoms per conventional cell
Symmetry operations
32 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
Th3Th2a20.00000.00000.0000
Cr1Cr4d40.00000.50000.2500
Si2Si4e40.00000.00000.3740

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 10 atoms drawn above are these sites multiplied by all 32 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

A2B2C_tI10_139_d_e_a-003: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol tI10, then the space-group number 139, then the Wyckoff letters occupied by each element in turn (Th: 2a; Cr: 4d; Si: 4e). Two structures with the same label are the same arrangement with different cell parameters or coordinates.

Other compounds with this structure

BaAl₂Ge₂, BaFe₂As₂, BaFe₂P₂, BaMg₂Si₂, BaMg₂Ge₂, BaMn₂Ge₂, BaNi₂As₂, BaNi₂Ge₂, BaRh₂B₂, CaAl₂Zn₂, CaAu₂Si₂, CaFe₂As₂, CaMn₂Ge₂, CaNi₂Ge₂, CaPd₂As₂, CeAl₂Ga₂, CeCu₂Si₂, CeMn₂Ge₂, CeRh₂Ge₂, CeRh₂Si₂, CeRu₂Si₂, CsCo₂As₂, CsCo₂P₂, CsFe₂As₂, CsFe₂P₂, CsIr₂As₂, CsIr₂P₂, CsRh₂As₂, CsRh₂P₂, CsRu₂As₂, CsRu₂P₂, DyCr₂Si₂, EuCo₂As₂, EuCo₂P₂, EuFe₂P₂, EuRh₂P₂, GdRu₂Ge₂, GdRu₂Si₂, GdRu₂Sn₂, KNi₂S₂, KNi₂Se₂, LaCo₂P₂, LaRu₂P₂, LuFe₂B₂, LuRu₂Si₂, PuCr₂Si₂, SrCo₂P₂, SrFe₂As₂, SrFe₂P₂, SrNi₂P₂, SrRh₂As₂, SrRh₂P₂, SrRu₂P₂, ThCr₂Si₂, ThCu₂Si₂, ThMn₂Ge₂, ThMn₂Si₂, ThNi₂Si₂, TlCu₂Se₂, UCr₂Si₂, URu₂Si₂, YFe₂Ge₂, YNi₂

Source

Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A2B2C_tI10_139_d_e_a-003 (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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