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
SettingUnit 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
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Ba3 | Ba | 1a | 1 | 0.0000 | 0.0000 | 0.0000 |
| Fe4 | Fe | 2c | 2 | 0.3333 | 0.6667 | 0.0000 |
| Al1 | Al | 3f | 3 | 0.5000 | 0.0000 | 0.0000 |
| Al2 | Al | 6m | 6 | 0.2120 | 0.4240 | 0.5000 |
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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