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Crystal Lab › Prototype structures › Orthorhombic

TiAl₂Br₈

Orthorhombic · space group Pnn2 (No. 34) · Pearson oP22

Symmetry elements and Wyckoff positions (interactive)

TiAl₂Br₈ in Pnn2

Setting
Loading the group…
x = 0.10, y = 0.17, z = 0.08

Unit cell

Lattice constants
a = 6.274 Å, b = 12.801 Å, c = 8.676 Å; α = 90.00°, β = 90.00°, γ = 90.00°
Cell volume
696.8 ų
Atoms in the conventional cell
22 (Ti 2, Al 4, Br 16)
Formula units Z
2
Pearson symbol
oP22 — orthorhombic, primitive lattice, 22 atoms per conventional cell
Symmetry operations
4 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
Ti6Ti2a20.00000.00000.5000
Al1Al4c40.60500.81350.4990
Br2Br4c40.73490.67960.0090
Br3Br4c40.74300.90750.3064
Br4Br4c40.23880.59350.2196
Br5Br4c40.71310.64590.5130

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 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

A2B8C_oP22_34_c_4c_a-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oP22, then the space-group number 34, then the Wyckoff letters occupied by each element in turn (Ti: 2a; Al: 4c; Br: 4c; Br: 4c; Br: 4c; Br: 4c). 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 A2B8C_oP22_34_c_4c_a-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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