Crystal Lab › Prototype structures › Orthorhombic
Ni₃Si₂
Orthorhombic · space group Cmc21 (No. 36) · Pearson oC80
Symmetry elements and Wyckoff positions (interactive)
Ni₃Si₂ in Cmc21
SettingUnit cell
- Lattice constants
- a = 12.229 Å, b = 10.805 Å, c = 6.924 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 914.9 ų
- Atoms in the conventional cell
- 80 (Ni 48, Si 32)
- Formula units Z
- 16
- Pearson symbol
- oC80 — orthorhombic, base-centred lattice, 80 atoms per conventional cell
- Symmetry operations
- 8 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Ni1 | Ni | 4a | 4 | 0.0000 | 0.0000 | 0.0000 |
| Ni2 | Ni | 4a | 4 | 0.0000 | 0.2345 | 0.0240 |
| Ni3 | Ni | 4a | 4 | 0.0000 | 0.2330 | 0.4000 |
| Ni4 | Ni | 4a | 4 | 0.0000 | 0.3814 | 0.7140 |
| Si10 | Si | 4a | 4 | 0.0000 | 0.4090 | 0.2180 |
| Si9 | Si | 4a | 4 | 0.0000 | 0.1570 | 0.7120 |
| Ni5 | Ni | 8b | 8 | 0.6732 | 0.6177 | 0.5180 |
| Ni6 | Ni | 8b | 8 | 0.6723 | 0.6189 | 0.9000 |
| Ni7 | Ni | 8b | 8 | 0.1972 | 0.2467 | 0.2170 |
| Ni8 | Ni | 8b | 8 | 0.1824 | 0.4975 | 0.2250 |
| Si11 | Si | 8b | 8 | 0.6200 | 0.5590 | 0.2140 |
| Si12 | Si | 8b | 8 | 0.1520 | 0.3440 | 0.5060 |
| Si13 | Si | 8b | 8 | 0.1510 | 0.3430 | 0.9200 |
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 80 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
A3B2_oC80_36_4a4b_2a3b-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oC80, then the space-group number 36, then the Wyckoff letters occupied by each element in turn (Ni: 4a; Ni: 4a; Ni: 4a; Ni: 4a; Si: 4a; Si: 4a; Ni: 8b; Ni: 8b; Ni: 8b; Ni: 8b; Si: 8b; Si: 8b; Si: 8b). 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 A3B2_oC80_36_4a4b_2a3b-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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