Crystal Lab › Prototype structures › Orthorhombic
α-UB₂C BCU₂
Orthorhombic · space group Pmma (No. 51) · Pearson oP8
Symmetry elements and Wyckoff positions (interactive)
α-UB₂C in Pmma
SettingUnit cell
- Lattice constants
- a = 6.034 Å, b = 3.518 Å, c = 4.107 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 87.2 ų
- Atoms in the conventional cell
- 8 (C 2, U 2, B 4)
- Formula units Z
- 2
- Pearson symbol
- oP8 — orthorhombic, primitive lattice, 8 atoms per conventional cell
- Symmetry operations
- 8 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| C2 | C | 2a | 2 | 0.0000 | 0.0000 | 0.0000 |
| U3 | U | 2f | 2 | 0.2500 | 0.5000 | 0.7981 |
| B1 | B | 4i | 4 | 0.9018 | 0.0000 | 0.6602 |
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 8 atoms drawn above are these sites multiplied by all 8 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
A2BC_oP8_51_i_a_f-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oP8, then the space-group number 51, then the Wyckoff letters occupied by each element in turn (C: 2a; U: 2f; B: 4i). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Note: α-UB₂C.
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A2BC_oP8_51_i_a_f-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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