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Crystal Lab › Prototype structures › Orthorhombic

SmNiGe₃

Orthorhombic · space group Cmmm (No. 65) · Pearson oC20

Symmetry elements and Wyckoff positions (interactive)

SmNiGe₃ in Cmmm

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

Unit cell

Lattice constants
a = 21.645 Å, b = 4.082 Å, c = 4.016 Å; α = 90.00°, β = 90.00°, γ = 90.00°
Cell volume
354.8 ų
Atoms in the conventional cell
20 (Ge 12, Ni 4, Sm 4)
Formula units Z
4
Pearson symbol
oC20 — orthorhombic, base-centred lattice, 20 atoms per conventional cell
Symmetry operations
16 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
Ge1Ge4g40.71630.00000.0000
Ge2Ge4g40.94320.00000.0000
Ni4Ni4g40.60950.00000.0000
Ge3Ge4h40.55680.00000.5000
Sm5Sm4h40.83170.00000.5000

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 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

A3BC_oC20_65_2gh_g_h-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oC20, then the space-group number 65, then the Wyckoff letters occupied by each element in turn (Ge: 4g; Ge: 4g; Ni: 4g; Ge: 4h; Sm: 4h). Two structures with the same label are the same arrangement with different cell parameters or coordinates.

Other compounds with this structure

CeNiGe₃, DyNiGe₃, DyNiSi₃, ErNiGe₃, ErNiSi₃, GdNiGe₃, HoNiGe₃, HoNiSi₃, LuNiGe₃, NdNiGe₃, PrNiGe₃, SmNiGe₃, TbNiGe₃, TmNiGe₃, YNiGe₃, YbNiGe₃, YbNiSi₃ <!--beginning with an

Source

Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A3BC_oC20_65_2gh_g_h-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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