α-Alum [KAl(SO₄)₂ cdot 12H₂O, H4₁₃]

Unit cell

Lattice constants

a = 12.135 Å, b = 12.135 Å, c = 12.135 Å; α = 90.00°, β = 90.00°, γ = 90.00°

Cell volume

1787.0 ų

Atoms in the conventional cell

224 (Al 4, K 4, O 112, S 8, H 96)

Formula units Z

4

Pearson symbol

cP224 — cubic, primitive lattice, 224 atoms per conventional cell

Symmetry operations

24 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 224 atoms drawn above are these sites multiplied by all 24 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

AB24CD28E2_cP224_205_a_4d_b_2c4d_c-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol cP224, then the space-group number 205, then the Wyckoff letters occupied by each element in turn (Al: 4a; K: 4b; O: 8c; O: 8c; S: 8c; H: 24d; H: 24d; H: 24d; H: 24d; O: 24d; O: 24d; O: 24d; O: 24d). Two structures with the same label are the same arrangement with different cell parameters or coordinates.

Other compounds with this structure

NH₄Al(SO₄)₂ cdot 12H₂O, KCr(SO₄)₂ cdot 12H₂O, RbAl(SO₄)₂ cdot 12H₂O, KAl(SeO₄)₂ cdot 12H₂O <!--beginning with an

Note: H4₁₃, α-Alum.

Source

Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry AB24CD28E2_cP224_205_a_4d_b_2c4d_c-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.