Crystal Lab › Prototype structures › Tetragonal
θ-AlF₃
Tetragonal · space group P4/nmm (No. 129) · Pearson tP64
Symmetry elements and Wyckoff positions (interactive)
θ-AlF₃ in P4/nmm
SettingUnit cell
- Lattice constants
- a = 10.184 Å, b = 10.184 Å, c = 7.173 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 744.0 ų
- Atoms in the conventional cell
- 64 (Al 16, F 48)
- Formula units Z
- 16
- Pearson symbol
- tP64 — tetragonal, primitive lattice, 64 atoms per conventional cell
- Symmetry operations
- 16 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Al1 | Al | 2c | 2 | 0.2500 | 0.2500 | 0.9068 |
| Al2 | Al | 2c | 2 | 0.2500 | 0.2500 | 0.4137 |
| F5 | F | 2c | 2 | 0.2500 | 0.2500 | 0.1573 |
| F6 | F | 2c | 2 | 0.2500 | 0.2500 | 0.6645 |
| Al3 | Al | 4d | 4 | 0.0000 | 0.0000 | 0.0000 |
| F7 | F | 4f | 4 | 0.7500 | 0.2500 | 0.2433 |
| F8 | F | 8h | 8 | 0.1262 | 0.8738 | 0.5000 |
| Al4 | Al | 8i | 8 | 0.2500 | 0.9138 | 0.3274 |
| F9 | F | 8i | 8 | 0.2500 | 0.0770 | 0.4130 |
| F10 | F | 8j | 8 | 0.1280 | 0.1280 | 0.9077 |
| F11 | F | 16k | 16 | 0.1223 | 0.9478 | 0.1610 |
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 64 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
AB3_tP64_129_2cdi_2cfhijk-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol tP64, then the space-group number 129, then the Wyckoff letters occupied by each element in turn (Al: 2c; Al: 2c; F: 2c; F: 2c; Al: 4d; F: 4f; F: 8h; Al: 8i; F: 8i; F: 8j; F: 16k). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Note: \theta-AlF₃.
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry AB3_tP64_129_2cdi_2cfhijk-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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