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Crystal Lab › Prototype structures › Orthorhombic

Clinobarylite (BaBe₂Si₂O₇)

Orthorhombic · space group Pmn21 (No. 31) · Pearson oP24 · mineral: clinobarylite

Symmetry elements and Wyckoff positions (interactive)

Clinobarylite (BaBe₂Si₂O₇) in Pmn21

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

Unit cell

Lattice constants
a = 11.649 Å, b = 4.918 Å, c = 4.675 Å; α = 90.00°, β = 90.00°, γ = 90.00°
Cell volume
267.8 ų
Atoms in the conventional cell
24 (Ba 2, O 14, Be 4, Si 4)
Formula units Z
2
Pearson symbol
oP24 — orthorhombic, primitive lattice, 24 atoms per conventional cell
Symmetry operations
4 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
Ba1Ba2a20.00000.79680.0905
O3O2a20.00000.22360.6793
Be2Be4b40.75110.16930.0849
O4O4b40.63900.35600.1367
O5O4b40.77690.13400.7298
O6O4b40.63270.72950.7284
Si7Si4b40.62830.67530.0692

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 24 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

AB2C7D2_oP24_31_a_b_a3b_b-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oP24, then the space-group number 31, then the Wyckoff letters occupied by each element in turn (Ba: 2a; O: 2a; Be: 4b; O: 4b; O: 4b; O: 4b; Si: 4b). Two structures with the same label are the same arrangement with different cell parameters or coordinates.

Note: Clinobarylite.

Source

Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry AB2C7D2_oP24_31_a_b_a3b_b-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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