Crystal Lab › Prototype structures › Trigonal
Sn₃P₄
Trigonal · space group R-3m (No. 166) · Pearson hR19
Symmetry elements and Wyckoff positions (interactive)
Sn₃P₄ in R-3m
SettingUnit cell
- Lattice constants
- a = 4.429 Å, b = 4.429 Å, c = 28.361 Å; α = 90.00°, β = 90.00°, γ = 120.00°
- Cell volume
- 481.8 ų
- Atoms in the conventional cell
- 57 (Sn 9, P 48)
- Formula units Z
- 3
- Pearson symbol
- hR19 — hexagonal / trigonal, rhombohedral lattice, 19 atoms per conventional cell
- Symmetry operations
- 36 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Sn5 | Sn | 3a | 3 | 0.0000 | 0.0000 | 0.0000 |
| P1 | P | 6c | 6 | 0.0000 | 0.0000 | 0.4330 |
| P2 | P | 6c | 6 | 0.0000 | 0.0000 | 0.3574 |
| Sn6 | Sn | 6c | 6 | 0.0000 | 0.0000 | 0.7945 |
| P3 | P | 18h | 18 | 0.2043 | 0.7957 | 0.0711 |
| P4 | P | 18h | 18 | 0.4718 | 0.5282 | 0.0528 |
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 57 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
A16B3_hR19_166_2c2h_ac-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol hR19, then the space-group number 166, then the Wyckoff letters occupied by each element in turn (Sn: 3a; P: 6c; P: 6c; Sn: 6c; P: 18h; P: 18h). 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 A16B3_hR19_166_2c2h_ac-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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