Crystal Lab › Prototype structures › Orthorhombic
High-Temperature AlPO₄-25 AlO₄P
Orthorhombic · space group Cmme (No. 67) · Pearson oC72
Symmetry elements and Wyckoff positions (interactive)
High-Temperature AlPO₄-25 in Cmme
SettingUnit cell
- Lattice constants
- a = 15.203 Å, b = 8.408 Å, c = 9.449 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 1207.9 ų
- Atoms in the conventional cell
- 72 (O 48, Al 24)
- Formula units Z
- 24
- Pearson symbol
- oC72 — orthorhombic, base-centred lattice, 72 atoms per conventional cell
- Symmetry operations
- 16 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| O3 | O | 4c | 4 | 0.0000 | 0.0000 | 0.0000 |
| O4 | O | 4g | 4 | 0.0000 | 0.2500 | 0.8924 |
| O5 | O | 8i | 8 | 0.1225 | 0.0000 | 0.5000 |
| O6 | O | 8l | 8 | 0.2500 | 0.0000 | 0.6983 |
| Al1 | Al | 8m | 8 | 0.0000 | 0.0652 | 0.8434 |
| O7 | O | 8n | 8 | 0.6529 | 0.2500 | 0.6692 |
| Al2 | Al | 16o | 16 | 0.1518 | 0.9487 | 0.6465 |
| O8 | O | 16o | 16 | 0.0875 | 0.9997 | 0.7683 |
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 72 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
AB2_oC72_67_mo_cgilno-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oC72, then the space-group number 67, then the Wyckoff letters occupied by each element in turn (O: 4c; O: 4g; O: 8i; O: 8l; Al: 8m; O: 8n; Al: 16o; O: 16o). 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 AB2_oC72_67_mo_cgilno-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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