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Crystal Lab › Prototype structures › Tetragonal

Na₃Hg₂

Tetragonal · space group P42/mnm (No. 136) · Pearson tP20

Symmetry elements and Wyckoff positions (interactive)

Na₃Hg₂ in P42/mnm

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

Unit cell

Lattice constants
a = 8.520 Å, b = 8.520 Å, c = 7.800 Å; α = 90.00°, β = 90.00°, γ = 90.00°
Cell volume
566.2 ų
Atoms in the conventional cell
20 (Na 12, Hg 8)
Formula units Z
4
Pearson symbol
tP20 — tetragonal, primitive lattice, 20 atoms per conventional cell
Symmetry operations
16 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
Na2Na4c40.00000.50000.0000
Na3Na4f40.36800.36800.0000
Na4Na4g40.21000.79000.0000
Hg1Hg8j80.12500.12500.1900

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

A2B3_tP20_136_j_cfg-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol tP20, then the space-group number 136, then the Wyckoff letters occupied by each element in turn (Na: 4c; Na: 4f; Na: 4g; Hg: 8j). Two structures with the same label are the same arrangement with different cell parameters or coordinates.

Other compounds with this structure

Al₂Zr₃ <!--beginning with an

Source

Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A2B3_tP20_136_j_cfg-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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