Crystal Lab › Prototype structures › Orthorhombic
ThFe₂SiC
Orthorhombic · space group Cmcm (No. 63) · Pearson oC20
Symmetry elements and Wyckoff positions (interactive)
ThFe₂SiC in Cmcm
SettingUnit cell
- Lattice constants
- a = 3.863 Å, b = 10.806 Å, c = 6.950 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 290.1 ų
- Atoms in the conventional cell
- 20 (C 4, Si 4, Th 4, Fe 8)
- Formula units Z
- 4
- Pearson symbol
- oC20 — orthorhombic, base-centred lattice, 20 atoms per conventional cell
- Symmetry operations
- 16 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| C1 | C | 4a | 4 | 0.0000 | 0.0000 | 0.0000 |
| Si3 | Si | 4c | 4 | 0.0000 | 0.2719 | 0.2500 |
| Th4 | Th | 4c | 4 | 0.0000 | 0.5527 | 0.2500 |
| Fe2 | Fe | 8f | 8 | 0.0000 | 0.1658 | 0.5611 |
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 20 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
AB2CD_oC20_63_a_f_c_c-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oC20, then the space-group number 63, then the Wyckoff letters occupied by each element in turn (C: 4a; Si: 4c; Th: 4c; Fe: 8f). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Other compounds with this structure
ErFe₂SiC, GdFe₂SiC, HoFe₂SiC, LuFe₂SiC, SmFe₂SiC, TbFe₂SiC, TmFe₂SiC, UFe₂SiC, YFe₂SiC <!--beginning with an
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry AB2CD_oC20_63_a_f_c_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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