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Crystal Lab › Prototype structures › Orthorhombic

α-UB₂C BCU₂

Orthorhombic · space group Pmma (No. 51) · Pearson oP8

Symmetry elements and Wyckoff positions (interactive)

α-UB₂C in Pmma

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

Unit cell

Lattice constants
a = 6.034 Å, b = 3.518 Å, c = 4.107 Å; α = 90.00°, β = 90.00°, γ = 90.00°
Cell volume
87.2 ų
Atoms in the conventional cell
8 (C 2, U 2, B 4)
Formula units Z
2
Pearson symbol
oP8 — orthorhombic, primitive lattice, 8 atoms per conventional cell
Symmetry operations
8 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
C2C2a20.00000.00000.0000
U3U2f20.25000.50000.7981
B1B4i40.90180.00000.6602

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 8 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

A2BC_oP8_51_i_a_f-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oP8, then the space-group number 51, then the Wyckoff letters occupied by each element in turn (C: 2a; U: 2f; B: 4i). Two structures with the same label are the same arrangement with different cell parameters or coordinates.

Note: α-UB₂C.

Source

Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A2BC_oP8_51_i_a_f-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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