Crystal Lab › Prototype structures › Hexagonal
Ti₃Al₂N₂
Hexagonal · space group P63mc (No. 186) · Pearson hP22
Symmetry elements and Wyckoff positions (interactive)
Ti₃Al₂N₂ in P63mc
SettingUnit cell
- Lattice constants
- a = 2.987 Å, b = 2.987 Å, c = 23.350 Å; α = 90.00°, β = 90.00°, γ = 120.00°
- Cell volume
- 180.5 ų
- Atoms in the conventional cell
- 22 (Al 4, Ti 10, N 8)
- Formula units Z
- 2
- Pearson symbol
- hP22 — hexagonal / trigonal, primitive lattice, 22 atoms per conventional cell
- Symmetry operations
- 12 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Al1 | Al | 2a | 2 | 0.0000 | 0.0000 | 0.1500 |
| Ti2 | Ti | 2a | 2 | 0.0000 | 0.0000 | 0.3500 |
| Al3 | Al | 2b | 2 | 0.3333 | 0.6667 | 0.2500 |
| N4 | N | 2b | 2 | 0.3333 | 0.6667 | 0.6000 |
| N5 | N | 2b | 2 | 0.3333 | 0.6667 | 0.9000 |
| N6 | N | 2b | 2 | 0.3333 | 0.6667 | 0.1000 |
| N7 | N | 2b | 2 | 0.3333 | 0.6667 | 0.4000 |
| Ti8 | Ti | 2b | 2 | 0.3333 | 0.6667 | 0.0500 |
| Ti9 | Ti | 2b | 2 | 0.3333 | 0.6667 | 0.4500 |
| Ti10 | Ti | 2b | 2 | 0.3333 | 0.6667 | 0.5500 |
| Ti11 | Ti | 2b | 2 | 0.3333 | 0.6667 | 0.9500 |
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 22 atoms drawn above are these sites multiplied by all 12 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
A2B4C5_hP22_186_ab_4b_a4b-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol hP22, then the space-group number 186, then the Wyckoff letters occupied by each element in turn (Al: 2a; Ti: 2a; Al: 2b; N: 2b; N: 2b; N: 2b; N: 2b; Ti: 2b; Ti: 2b; Ti: 2b; Ti: 2b). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A2B4C5_hP22_186_ab_4b_a4b-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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