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Crystal Lab › Prototype structures › Orthorhombic

Na₂Mo₂O₇

Orthorhombic · space group Cmce (No. 64) · Pearson oC88

Symmetry elements and Wyckoff positions (interactive)

Na₂Mo₂O₇ in Cmce

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

Unit cell

Lattice constants
a = 7.170 Å, b = 11.830 Å, c = 14.700 Å; α = 90.00°, β = 90.00°, γ = 90.00°
Cell volume
1246.9 ų
Atoms in the conventional cell
88 (Na 16, Mo 16, O 56)
Formula units Z
8
Pearson symbol
oC88 — orthorhombic, base-centred lattice, 88 atoms per conventional cell
Symmetry operations
16 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
Na3Na8d80.25000.00000.0000
Mo1Mo8e80.25000.08000.2500
Mo2Mo8f80.00000.25000.0800
Na4Na8f80.00000.36000.3000
O5O8f80.00000.08000.2700
O6O8f80.00000.41000.1300
O7O8f80.00000.35000.4900
O8O16g160.71000.71000.1600
O9O16g160.71000.99000.3400

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 88 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

A2B2C7_oC88_64_ef_df_3f2g-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oC88, then the space-group number 64, then the Wyckoff letters occupied by each element in turn (Na: 8d; Mo: 8e; Mo: 8f; Na: 8f; O: 8f; O: 8f; O: 8f; O: 16g; O: 16g). Two structures with the same label are the same arrangement with different cell parameters or coordinates.

Other compounds with this structure

Na₂W₂O₇ <!--beginning with an

Source

Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A2B2C7_oC88_64_ef_df_3f2g-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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