Crystal Lab › Prototype structures › Hexagonal
Sr₂Be₂B₂O₇
Hexagonal · space group P-6c2 (No. 188) · Pearson hP26
Symmetry elements and Wyckoff positions (interactive)
Sr₂Be₂B₂O₇ in P-6c2
SettingUnit cell
- Lattice constants
- a = 4.683 Å, b = 4.683 Å, c = 15.311 Å; α = 90.00°, β = 90.00°, γ = 120.00°
- Cell volume
- 290.8 ų
- Atoms in the conventional cell
- 26 (Sr 4, O 14, Be 4, B 4)
- Formula units Z
- 2
- Pearson symbol
- hP26 — hexagonal / trigonal, primitive lattice, 26 atoms per conventional cell
- Symmetry operations
- 12 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Sr5 | Sr | 2a | 2 | 1.0000 | 0.0000 | 0.0000 |
| Sr6 | Sr | 2b | 2 | 1.0000 | 0.0000 | 0.2500 |
| O3 | O | 2c | 2 | 0.3333 | 0.6667 | 0.0000 |
| Be2 | Be | 4h | 4 | 0.3333 | 0.6667 | 0.1066 |
| B1 | B | 4i | 4 | 0.6667 | 0.3333 | 0.1279 |
| O4 | O | 12l | 12 | 0.6289 | 0.0221 | 0.1382 |
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 26 atoms drawn above are these sites multiplied by all 12 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
A2B2C7D2_hP26_188_i_h_cl_ab-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol hP26, then the space-group number 188, then the Wyckoff letters occupied by each element in turn (Sr: 2a; Sr: 2b; O: 2c; Be: 4h; B: 4i; O: 12l). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A2B2C7D2_hP26_188_i_h_cl_ab-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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