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Crystal Lab › Prototype structures › Hexagonal

BaFe₂Al₉

Hexagonal · space group P6/mmm (No. 191) · Pearson hP12

Symmetry elements and Wyckoff positions (interactive)

BaFe₂Al₉ in P6/mmm

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

Unit cell

Lattice constants
a = 8.040 Å, b = 8.040 Å, c = 3.890 Å; α = 90.00°, β = 90.00°, γ = 120.00°
Cell volume
217.8 ų
Atoms in the conventional cell
12 (Ba 1, Fe 2, Al 9)
Formula units Z
1
Pearson symbol
hP12 — hexagonal / trigonal, primitive lattice, 12 atoms per conventional cell
Symmetry operations
24 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
Ba3Ba1a10.00000.00000.0000
Fe4Fe2c20.33330.66670.0000
Al1Al3f30.50000.00000.0000
Al2Al6m60.21200.42400.5000

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 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

A9BC2_hP12_191_fm_a_c-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 191, then the Wyckoff letters occupied by each element in turn (Ba: 1a; Fe: 2c; Al: 3f; Al: 6m). Two structures with the same label are the same arrangement with different cell parameters or coordinates.

Other compounds with this structure

BaCo₂Al₉, BaIr₂In₉, BaNi₂Al₉, CaCo₂Al₉, EuCo₂Al₉, KCo₂In₉, KNi₂In₉, SrCo₂Al₉, SrNi₂Al₉ <!--beginning with an

Source

Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A9BC2_hP12_191_fm_a_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.

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