Crystal Lab › Prototype structures › Orthorhombic
α-PbO OPb
Orthorhombic · space group Cmme (No. 67) · Pearson oC8
Symmetry elements and Wyckoff positions (interactive)
α-PbO in Cmme
SettingUnit cell
- Lattice constants
- a = 5.612 Å, b = 5.609 Å, c = 4.992 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 157.2 ų
- Atoms in the conventional cell
- 8 (O 4, Pb 4)
- Formula units Z
- 4
- Pearson symbol
- oC8 — orthorhombic, base-centred lattice, 8 atoms per conventional cell
- Symmetry operations
- 16 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| O1 | O | 4a | 4 | 0.2500 | 0.0000 | 0.0000 |
| Pb2 | Pb | 4g | 4 | 0.0000 | 0.2500 | 0.2358 |
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 16 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
AB_oC8_67_a_g-002: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oC8, then the space-group number 67, then the Wyckoff letters occupied by each element in turn (O: 4a; Pb: 4g). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Other compounds with this structure
SnO, α-FeSe <!--beginning with an
Note: α-PbO.
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry AB_oC8_67_a_g-002 (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.