Crystal Lab › Prototype structures › Orthorhombic
α-Ni₇S₆
Orthorhombic · space group Cmcm (No. 63) · Pearson oC56
Symmetry elements and Wyckoff positions (interactive)
α-Ni₇S₆ in Cmcm
SettingUnit cell
- Lattice constants
- a = 3.274 Å, b = 11.359 Å, c = 16.157 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 600.9 ų
- Atoms in the conventional cell
- 56 (Ni 36, S 20)
- Formula units Z
- 4
- Pearson symbol
- oC56 — orthorhombic, base-centred lattice, 56 atoms per conventional cell
- Symmetry operations
- 16 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Ni1 | Ni | 4c | 4 | 0.0000 | 0.8448 | 0.2500 |
| S6 | S | 4c | 4 | 0.0000 | 0.6418 | 0.2500 |
| Ni2 | Ni | 8f | 8 | 0.0000 | 0.2838 | 0.6277 |
| Ni3 | Ni | 8f | 8 | 0.0000 | 0.9601 | 0.6728 |
| Ni4 | Ni | 8f | 8 | 0.0000 | 0.6836 | 0.5289 |
| Ni5 | Ni | 8f | 8 | 0.0000 | 0.5195 | 0.5346 |
| S7 | S | 8f | 8 | 0.0000 | 0.8793 | 0.5450 |
| S8 | S | 8f | 8 | 0.0000 | 0.6142 | 0.6527 |
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 56 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
A9B5_oC56_63_c4f_c2f-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oC56, then the space-group number 63, then the Wyckoff letters occupied by each element in turn (Ni: 4c; S: 4c; Ni: 8f; Ni: 8f; Ni: 8f; Ni: 8f; S: 8f; S: 8f). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Note: α-Ni₇S₆.
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A9B5_oC56_63_c4f_c2f-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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