Crystal Lab › Prototype structures › Orthorhombic
K₂Cu₃Ge₄O₁₂
Orthorhombic · space group Cmcm (No. 63) · Pearson oC84
Symmetry elements and Wyckoff positions (interactive)
K₂Cu₃Ge₄O₁₂ in Cmcm
SettingUnit cell
- Lattice constants
- a = 14.079 Å, b = 5.780 Å, c = 13.892 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 1130.5 ų
- Atoms in the conventional cell
- 84 (Cu 12, O 48, K 8, Ge 16)
- Formula units Z
- 4
- Pearson symbol
- oC84 — orthorhombic, base-centred lattice, 84 atoms per conventional cell
- Symmetry operations
- 16 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Cu1 | Cu | 4a | 4 | 0.0000 | 0.0000 | 0.0000 |
| Cu2 | Cu | 8e | 8 | 0.7917 | 0.0000 | 0.0000 |
| O5 | O | 8f | 8 | 0.0000 | 0.4484 | 0.6191 |
| K4 | K | 8g | 8 | 0.1643 | 0.8920 | 0.2500 |
| O6 | O | 8g | 8 | 0.1309 | 0.3429 | 0.2500 |
| Ge3 | Ge | 16h | 16 | 0.3898 | 0.0952 | 0.6273 |
| O7 | O | 16h | 16 | 0.3975 | 0.3691 | 0.5752 |
| O8 | O | 16h | 16 | 0.3008 | 0.9072 | 0.5949 |
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 84 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
A3B4C2D12_oC84_63_ae_h_g_fg2h-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oC84, then the space-group number 63, then the Wyckoff letters occupied by each element in turn (Cu: 4a; Cu: 8e; O: 8f; K: 8g; O: 8g; Ge: 16h; O: 16h; O: 16h). 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 A3B4C2D12_oC84_63_ae_h_g_fg2h-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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