Crystal Lab › Prototype structures › Orthorhombic
Ag₇Ca₂
Orthorhombic · space group Cmcm (No. 63) · Pearson oC36
Symmetry elements and Wyckoff positions (interactive)
Ag₇Ca₂ in Cmcm
SettingUnit cell
- Lattice constants
- a = 9.478 Å, b = 5.525 Å, c = 14.079 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 737.3 ų
- Atoms in the conventional cell
- 36 (Ag 28, Ca 8)
- Formula units Z
- 4
- Pearson symbol
- oC36 — orthorhombic, base-centred lattice, 36 atoms per conventional cell
- Symmetry operations
- 16 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Ag1 | Ag | 4c | 4 | 0.0000 | 0.8267 | 0.2500 |
| Ca4 | Ca | 8f | 8 | 0.0000 | 0.3219 | 0.1147 |
| Ag2 | Ag | 8g | 8 | 0.7509 | 0.5775 | 0.2500 |
| Ag3 | Ag | 16h | 16 | 0.8347 | 0.8293 | 0.0765 |
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 36 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
A7B2_oC36_63_cgh_f-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oC36, then the space-group number 63, then the Wyckoff letters occupied by each element in turn (Ag: 4c; Ca: 8f; Ag: 8g; Ag: 16h). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Other compounds with this structure
Ag₇Yb₂ <!--beginning with an
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A7B2_oC36_63_cgh_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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