Crystal Lab › Prototype structures › Orthorhombic
SmNiGe₃
Orthorhombic · space group Cmmm (No. 65) · Pearson oC20
Symmetry elements and Wyckoff positions (interactive)
SmNiGe₃ in Cmmm
SettingUnit 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
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Ge1 | Ge | 4g | 4 | 0.7163 | 0.0000 | 0.0000 |
| Ge2 | Ge | 4g | 4 | 0.9432 | 0.0000 | 0.0000 |
| Ni4 | Ni | 4g | 4 | 0.6095 | 0.0000 | 0.0000 |
| Ge3 | Ge | 4h | 4 | 0.5568 | 0.0000 | 0.5000 |
| Sm5 | Sm | 4h | 4 | 0.8317 | 0.0000 | 0.5000 |
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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