Crystal Lab › Prototype structures › Trigonal
Shandite (Ni₃Pb₂S₂)
Trigonal · space group R-3m (No. 166) · Pearson hR7 · mineral: shandite
Symmetry elements and Wyckoff positions (interactive)
Shandite (Ni₃Pb₂S₂) in R-3m
SettingUnit cell
- Lattice constants
- a = 5.595 Å, b = 5.595 Å, c = 13.626 Å; α = 90.00°, β = 90.00°, γ = 120.00°
- Cell volume
- 369.4 ų
- Atoms in the conventional cell
- 21 (Pb 6, S 6, Ni 9)
- Formula units Z
- 3
- Pearson symbol
- hR7 — hexagonal / trigonal, rhombohedral lattice, 7 atoms per conventional cell
- Symmetry operations
- 36 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Pb2 | Pb | 3a | 3 | 0.0000 | 0.0000 | 0.0000 |
| Pb3 | Pb | 3b | 3 | 0.0000 | 0.0000 | 0.5000 |
| S4 | S | 6c | 6 | 0.0000 | 0.0000 | 0.2750 |
| Ni1 | Ni | 9d | 9 | 0.5000 | 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 21 atoms drawn above are these sites multiplied by all 36 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
A3B2C2_hR7_166_d_ab_c-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol hR7, then the space-group number 166, then the Wyckoff letters occupied by each element in turn (Pb: 3a; Pb: 3b; S: 6c; Ni: 9d). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Other compounds with this structure
Co₃In₂S₂, Co₃Sn₂S₂, Ni₃In₂S₂, Ni₃Sn₂S₂, Ni₃Tl₂S₂, O₃K₂Sn₂, Pd₃Bi₂S₂, Pd₃Pb₂S₂, Pt₃Pb₂S₂, Rh₃Pb₂S₂, Rh₃Tl₂S₂ <!--beginning with an
Note: Shandite.
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A3B2C2_hR7_166_d_ab_c-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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