Crystal Lab › Prototype structures › Orthorhombic
alpha_{H}'-Ca₂SiO₄ Ca₂O₄Si
Orthorhombic · space group Pnma (No. 62) · Pearson oP52
Symmetry elements and Wyckoff positions (interactive)
alpha_{H}'-Ca₂SiO₄ in Pnma
SettingUnit cell
- Lattice constants
- a = 6.871 Å, b = 5.601 Å, c = 9.556 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 367.8 ų
- Atoms in the conventional cell
- 52 (Si 4, Ca 16, O 32)
- Formula units Z
- 4
- Pearson symbol
- oP52 — orthorhombic, primitive lattice, 52 atoms per conventional cell
- Symmetry operations
- 8 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Si7 | Si | 4c | 4 | 0.7831 | 0.2500 | 0.5891 |
| Ca1 | Ca | 8d | 8 | 0.3326 | 0.2823 | 0.5732 |
| Ca2 | Ca | 8d | 8 | 0.9879 | 0.2952 | 0.2989 |
| O3 | O | 8d | 8 | 0.0050 | 0.3081 | 0.5545 |
| O4 | O | 8d | 8 | 0.7436 | 0.0308 | 0.7016 |
| O5 | O | 8d | 8 | 0.6658 | 0.1901 | 0.4449 |
| O6 | O | 8d | 8 | 0.7041 | 0.5030 | 0.6495 |
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 52 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
A4B8C_oP52_62_2d_4d_c-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oP52, then the space-group number 62, then the Wyckoff letters occupied by each element in turn (Si: 4c; Ca: 8d; Ca: 8d; O: 8d; O: 8d; O: 8d; O: 8d). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Other compounds with this structure
Sr₂SiO₄ <!--beginning with an
Note: \alpha_{H}'-Ca₂SiO₄.
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A4B8C_oP52_62_2d_4d_c-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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