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Crystal Lab › Prototype structures › Orthorhombic

Na₂Tl

Orthorhombic · space group C2221 (No. 20) · Pearson oC48

Symmetry elements and Wyckoff positions (interactive)

Na₂Tl in C2221

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

Unit cell

Lattice constants
a = 8.880 Å, b = 13.935 Å, c = 11.693 Å; α = 90.00°, β = 90.00°, γ = 90.00°
Cell volume
1446.8 ų
Atoms in the conventional cell
48 (Na 32, Tl 16)
Formula units Z
16
Pearson symbol
oC48 — orthorhombic, base-centred lattice, 48 atoms per conventional cell
Symmetry operations
8 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
Na2Na4a40.40800.00000.0000
Na1Na4b40.00000.93300.2500
Na3Na8c80.69400.20300.6710
Na4Na8c80.27800.87400.4570
Na5Na8c80.40500.63000.4160
Tl6Tl8c80.54840.21550.3820
Tl7Tl8c80.67760.95020.7770

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 8 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

A2B_oC48_20_ab3c_2c-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oC48, then the space-group number 20, then the Wyckoff letters occupied by each element in turn (Na: 4a; Na: 4b; Na: 8c; Na: 8c; Na: 8c; Tl: 8c; Tl: 8c). 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 A2B_oC48_20_ab3c_2c-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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