Crystal Lab › Prototype structures › Trigonal
CdCl₂
Trigonal · space group R-3m (No. 166) · Pearson hR3
Symmetry elements and Wyckoff positions (interactive)
CdCl₂ in R-3m
SettingUnit cell
- Lattice constants
- a = 3.995 Å, b = 3.995 Å, c = 17.749 Å; α = 90.00°, β = 90.00°, γ = 120.00°
- Cell volume
- 245.3 ų
- Atoms in the conventional cell
- 9 (Cd 3, Cl 6)
- Formula units Z
- 3
- Pearson symbol
- hR3 — hexagonal / trigonal, rhombohedral lattice, 3 atoms per conventional cell
- Symmetry operations
- 36 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Cd1 | Cd | 3a | 3 | 0.0000 | 0.0000 | 0.0000 |
| Cl2 | Cl | 6c | 6 | 0.0000 | 0.0000 | 0.2500 |
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 9 atoms drawn above are these sites multiplied by all 36 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
AB2_hR3_166_a_c-004: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol hR3, then the space-group number 166, then the Wyckoff letters occupied by each element in turn (Cd: 3a; Cl: 6c). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Other compounds with this structure
(Ag_{x}Bi_{1-x})I₂, (Ag_{x}Sb_{1-x})I₂, C(Sc_{x}Y_{1-x})₂, CDy₂, CHo₂, CSc₂, CY₂, CdBr₂, CdCl₂, CoCl₂, FeCl₂, MgCl₂, MnBr₂, MnCl₂ (Sacchite), NbS₂, NiBr₂, NiCl₂, NiI₂, OCs₂, PbI₂, TaSe₂, ZnBr₂, ZnI₂ <!--beginning with an
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry AB2_hR3_166_a_c-004 (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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