Corundum (α-alumina, Al₂O₃, D5₁)

Unit cell

Lattice constants

a = 4.761 Å, b = 4.761 Å, c = 12.995 Å; α = 90.00°, β = 90.00°, γ = 120.00°

Cell volume

255.1 ų

Atoms in the conventional cell

30 (Al 12, O 18)

Formula units Z

6

Pearson symbol

hR10 — hexagonal / trigonal, rhombohedral lattice, 10 atoms per conventional cell

Symmetry operations

36 per cell

Crystallographic sites

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 30 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

A2B3_hR10_167_c_e-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol hR10, then the space-group number 167, then the Wyckoff letters occupied by each element in turn (Al: 12c; O: 18e). Two structures with the same label are the same arrangement with different cell parameters or coordinates.

Other compounds with this structure

γ-Al₂S₃, Co₂O₃, Cr₂O₃ (eskolaite), Fe₂O₃ (hematite), (Fe, Ge)₂O₃, α-Ga₂O₃, In₂O₃, In₂S₃, (In, V)₂O₃, Lu₂S₃, (Mn, Sn)₂O₃, N₂Ca₃, Rh₂O₃, Ru₂C₃, Sc₂O₃, Ti₂O₃ (tistarite), Tm₂S₃, V₂O₃, Yb₂S₃, Lu₂S₃, Rh₂O₃, V₂O₃ (karelianite), Yb₂S₃ <!--beginning with an

Note: D5₁, Corundum, α-alumina.

Source

Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A2B3_hR10_167_c_e-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.