Crystal Lab › Prototype structures › Trigonal
Moissanite 9R (CSi)
Trigonal · space group R3m (No. 160) · Pearson hR6 · mineral: moissanite
Symmetry elements and Wyckoff positions (interactive)
Moissanite 9R (CSi) in R3m
SettingUnit cell
- Lattice constants
- a = 3.018 Å, b = 3.018 Å, c = 22.177 Å; α = 90.00°, β = 90.00°, γ = 120.00°
- Cell volume
- 174.9 ų
- Atoms in the conventional cell
- 18 (C 9, Si 9)
- Formula units Z
- 9
- Pearson symbol
- hR6 — hexagonal / trigonal, rhombohedral lattice, 6 atoms per conventional cell
- Symmetry operations
- 18 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| C1 | C | 3a | 3 | 0.0000 | 0.0000 | 0.0000 |
| C2 | C | 3a | 3 | 0.0000 | 0.0000 | 0.2222 |
| C3 | C | 3a | 3 | 0.0000 | 0.0000 | 0.7778 |
| Si4 | Si | 3a | 3 | 0.0000 | 0.0000 | 0.0833 |
| Si5 | Si | 3a | 3 | 0.0000 | 0.0000 | 0.3056 |
| Si6 | Si | 3a | 3 | 0.0000 | 0.0000 | 0.8611 |
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 18 atoms drawn above are these sites multiplied by all 18 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
AB_hR6_160_3a_3a-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol hR6, then the space-group number 160, then the Wyckoff letters occupied by each element in turn (C: 3a; C: 3a; C: 3a; Si: 3a; Si: 3a; Si: 3a). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Other compounds with this structure
ZnS <!--beginning with an
Note: 9R Moissanite.
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry AB_hR6_160_3a_3a-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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