Crystal Lab › Prototype structures › Orthorhombic
Na₂SO₄ (III)
Orthorhombic · space group Cmcm (No. 63) · Pearson oC28
Symmetry elements and Wyckoff positions (interactive)
Na₂SO₄ (III) in Cmcm
SettingUnit cell
- Lattice constants
- a = 5.600 Å, b = 8.950 Å, c = 6.990 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 350.3 ų
- Atoms in the conventional cell
- 28 (Na 8, S 4, O 16)
- Formula units Z
- 4
- Pearson symbol
- oC28 — orthorhombic, base-centred lattice, 28 atoms per conventional cell
- Symmetry operations
- 16 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Na1 | Na | 4a | 4 | 0.0000 | 0.0000 | 0.0000 |
| Na2 | Na | 4c | 4 | 0.0000 | 0.6850 | 0.2500 |
| S5 | S | 4c | 4 | 0.0000 | 0.3470 | 0.2500 |
| O3 | O | 8f | 8 | 0.0000 | 0.2500 | 0.0720 |
| O4 | O | 8g | 8 | 0.2800 | 0.9470 | 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 28 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
A2B4C_oC28_63_ac_fg_c-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oC28, then the space-group number 63, then the Wyckoff letters occupied by each element in turn (Na: 4a; Na: 4c; S: 4c; O: 8f; O: 8g). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Other compounds with this structure
Na₂CrO₄ <!--beginning with an
Note: Na₂SO₄ III.
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A2B4C_oC28_63_ac_fg_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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