Crystal Lab › Prototype structures › Orthorhombic
alpha_{L}'-Ca₂SiO₄ Ca₂O₄Si
Orthorhombic · space group Pna21 (No. 33) · Pearson oP84
Symmetry elements and Wyckoff positions (interactive)
alpha_{L}'-Ca₂SiO₄ in Pna21
SettingUnit cell
- Lattice constants
- a = 20.527 Å, b = 9.496 Å, c = 5.590 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 1089.6 ų
- Atoms in the conventional cell
- 84 (Ca 24, O 48, Si 12)
- Formula units Z
- 12
- Pearson symbol
- oP84 — orthorhombic, primitive lattice, 84 atoms per conventional cell
- Symmetry operations
- 4 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Ca1 | Ca | 4a | 4 | 0.7787 | 0.0726 | 0.7465 |
| Ca2 | Ca | 4a | 4 | 0.4417 | 0.0469 | 0.8011 |
| Ca3 | Ca | 4a | 4 | 0.1225 | 0.0794 | 0.7025 |
| Ca4 | Ca | 4a | 4 | 0.9958 | 0.8137 | 0.7228 |
| Ca5 | Ca | 4a | 4 | 0.6627 | 0.7836 | 0.7652 |
| Ca6 | Ca | 4a | 4 | 0.3275 | 0.8001 | 0.7453 |
| O10 | O | 4a | 4 | 0.6628 | 0.9287 | 0.2032 |
| O11 | O | 4a | 4 | 0.6080 | 0.4332 | 0.1838 |
| O12 | O | 4a | 4 | 0.5845 | 0.6998 | 0.0427 |
| O13 | O | 4a | 4 | 0.4988 | 0.5610 | 0.2906 |
| O14 | O | 4a | 4 | 0.5969 | 0.6734 | 0.4786 |
| O15 | O | 4a | 4 | 0.9500 | 0.4462 | 0.1919 |
| O16 | O | 4a | 4 | 0.9252 | 0.6903 | 0.0127 |
| O17 | O | 4a | 4 | 0.9213 | 0.6881 | 0.4742 |
| O18 | O | 4a | 4 | 0.8344 | 0.5495 | 0.1618 |
| O7 | O | 4a | 4 | 0.7585 | 0.8504 | 0.4906 |
| O8 | O | 4a | 4 | 0.7716 | 0.8674 | 0.0053 |
| O9 | O | 4a | 4 | 0.7811 | 0.0640 | 0.2141 |
| Si19 | Si | 4a | 4 | 0.2607 | 0.0680 | 0.7592 |
| Si20 | Si | 4a | 4 | 0.9284 | 0.0805 | 0.7557 |
| Si21 | Si | 4a | 4 | 0.5896 | 0.0959 | 0.7296 |
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 4 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
A2B4C_oP84_33_6a_12a_3a-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oP84, then the space-group number 33, then the Wyckoff letters occupied by each element in turn (Ca: 4a; Ca: 4a; Ca: 4a; Ca: 4a; Ca: 4a; Ca: 4a; O: 4a; O: 4a; O: 4a; O: 4a; O: 4a; O: 4a; O: 4a; O: 4a; O: 4a; O: 4a; O: 4a; O: 4a; Si: 4a; Si: 4a; Si: 4a). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Note: \alpha_{L}'-Ca₂SiO₄.
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A2B4C_oP84_33_6a_12a_3a-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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