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Crystal Lab › Prototype structures › Trigonal

Steklite [KAl(SO₄)₂, H3₂]

Trigonal · space group P321 (No. 150) · Pearson hP12 · Strukturbericht H32 · mineral: steklite

Symmetry elements and Wyckoff positions (interactive)

Steklite [KAl(SO₄)₂, H3₂] in P321

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

Unit cell

Lattice constants
a = 4.700 Å, b = 4.700 Å, c = 7.960 Å; α = 90.00°, β = 90.00°, γ = 120.00°
Cell volume
152.3 ų
Atoms in the conventional cell
12 (Al 1, K 1, O 8, S 2)
Formula units Z
1
Pearson symbol
hP12 — hexagonal / trigonal, primitive lattice, 12 atoms per conventional cell
Symmetry operations
6 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
Al1Al1a10.00000.00000.0000
K2K1b10.00000.00000.5000
O3O2d20.33330.66670.5160
S5S2d20.33330.66670.7220
O4O6g60.32800.34400.8170

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 12 atoms drawn above are these sites multiplied by all 6 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

ABC8D2_hP12_150_a_b_dg_d-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol hP12, then the space-group number 150, then the Wyckoff letters occupied by each element in turn (Al: 1a; K: 1b; O: 2d; S: 2d; O: 6g). Two structures with the same label are the same arrangement with different cell parameters or coordinates.

Other compounds with this structure

NH₄(Al, Fe)(SO₄)₂ (godovikovite), KCr(SO₄)₂, RbCr(SO₄)₂ <!--beginning with an

Note: H3₂, Steklite.

Source

Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry ABC8D2_hP12_150_a_b_dg_d-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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