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Crystal Lab › Prototype structures › Trigonal

Calcined AlPO₄-34 AlO₄P

Trigonal · space group R-3 (No. 148) · Pearson hR36

Symmetry elements and Wyckoff positions (interactive)

Calcined AlPO₄-34 in R-3

Setting
Loading the group…
x = 0.10, y = 0.17, z = 0.08

Unit cell

Lattice constants
a = 14.108 Å, b = 14.108 Å, c = 15.294 Å; α = 90.00°, β = 90.00°, γ = 120.00°
Cell volume
2636.2 ų
Atoms in the conventional cell
108 (Al 18, O 72, P 18)
Formula units Z
18
Pearson symbol
hR36 — hexagonal / trigonal, rhombohedral lattice, 36 atoms per conventional cell
Symmetry operations
18 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
Al1Al18f180.22560.22890.3967
O2O18f180.23910.11540.3663
O3O18f180.31080.98630.3337
O4O18f180.26100.00370.4909
O5O18f180.10670.90950.3747
P6P18f180.22920.00360.3919

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 108 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

AB4C_hR36_148_f_4f_f-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol hR36, then the space-group number 148, then the Wyckoff letters occupied by each element in turn (Al: 18f; O: 18f; O: 18f; O: 18f; O: 18f; P: 18f). Two structures with the same label are the same arrangement with different cell parameters or coordinates.

Note: AlPO₄-34.

Source

Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry AB4C_hR36_148_f_4f_f-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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