Crystal Lab › Prototype structures › Trigonal
TaTi₇ (BCC SQS-16)
Trigonal · space group R-3m (No. 166) · Pearson hR16
Symmetry elements and Wyckoff positions (interactive)
TaTi₇ (BCC SQS-16) in R-3m
SettingUnit cell
- Lattice constants
- a = 9.252 Å, b = 9.252 Å, c = 11.331 Å; α = 90.00°, β = 90.00°, γ = 120.00°
- Cell volume
- 840.0 ų
- Atoms in the conventional cell
- 48 (Ta 6, Ti 42)
- Formula units Z
- 6
- Pearson symbol
- hR16 — hexagonal / trigonal, rhombohedral lattice, 16 atoms per conventional cell
- Symmetry operations
- 36 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Ta1 | Ta | 6c | 6 | 0.0000 | 0.0000 | 0.8750 |
| Ti2 | Ti | 6c | 6 | 0.0000 | 0.0000 | 0.6250 |
| Ti3 | Ti | 18h | 18 | 0.8333 | 0.1667 | 0.7917 |
| Ti4 | Ti | 18h | 18 | 0.1667 | 0.8333 | 0.9583 |
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 48 atoms drawn above are these sites multiplied by all 36 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
AB7_hR16_166_c_c2h-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol hR16, then the space-group number 166, then the Wyckoff letters occupied by each element in turn (Ta: 6c; Ti: 6c; Ti: 18h; Ti: 18h). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Note: BCC SQS-16.
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry AB7_hR16_166_c_c2h-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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