Crystal Lab › Prototype structures › Trigonal
BaNi₂As₂O₈
Trigonal · space group R-3 (No. 148) · Pearson hR13
Symmetry elements and Wyckoff positions (interactive)
BaNi₂As₂O₈ in R-3
SettingUnit cell
- Lattice constants
- a = 4.936 Å, b = 4.936 Å, c = 23.610 Å; α = 90.00°, β = 90.00°, γ = 120.00°
- Cell volume
- 498.2 ų
- Atoms in the conventional cell
- 39 (Ba 3, As 6, Ni 6, O 24)
- Formula units Z
- 3
- Pearson symbol
- hR13 — hexagonal / trigonal, rhombohedral lattice, 13 atoms per conventional cell
- Symmetry operations
- 18 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Ba2 | Ba | 3a | 3 | 0.0000 | 0.0000 | 0.0000 |
| As1 | As | 6c | 6 | 0.0000 | 0.0000 | 0.4270 |
| Ni3 | Ni | 6c | 6 | 0.0000 | 0.0000 | 0.1670 |
| O4 | O | 6c | 6 | 0.0000 | 0.0000 | 0.3550 |
| O5 | O | 18f | 18 | 0.0000 | 0.6720 | 0.1130 |
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 39 atoms drawn above are these sites multiplied by all 18 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
A2BC2D8_hR13_148_c_a_c_cf-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol hR13, then the space-group number 148, then the Wyckoff letters occupied by each element in turn (Ba: 3a; As: 6c; Ni: 6c; O: 6c; O: 18f). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Other compounds with this structure
BaCo₂As₂O₈, BaCo₂P₂O₈, BaCo₂Sb₂O₈, BaMg₂As₂O₈, BaNi₂P₂O₈, BaNi₂V₂O₈ <!--beginning with an
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A2BC2D8_hR13_148_c_a_c_cf-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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