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Crystal Lab › Prototype structures › Orthorhombic

Dyscrasite (Ag_{3.15}Sb_{0.85})

Orthorhombic · space group Pmm2 (No. 25) · Pearson oP4 · mineral: dyscrasite

Symmetry elements and Wyckoff positions (interactive)

Dyscrasite (Ag_{3.15}Sb_{0.85}) in Pmm2

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

Unit cell

Lattice constants
a = 3.008 Å, b = 4.828 Å, c = 5.214 Å; α = 90.00°, β = 90.00°, γ = 90.00°
Cell volume
75.7 ų
Atoms in the conventional cell
4 (Ag 3, Sb 1)
Formula units Z
1
Pearson symbol
oP4 — orthorhombic, primitive lattice, 4 atoms per conventional cell
Symmetry operations
4 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
Ag1Ag1a10.00000.00000.0000
Ag2Ag1b10.00000.50000.3398
Ag3Ag1c10.50000.00000.4879
Sb4Sb1d10.50000.50000.8150

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 4 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

A3B_oP4_25_abc_d-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oP4, then the space-group number 25, then the Wyckoff letters occupied by each element in turn (Ag: 1a; Ag: 1b; Ag: 1c; Sb: 1d). Two structures with the same label are the same arrangement with different cell parameters or coordinates.

Note: Dyscrasite.

Source

Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A3B_oP4_25_abc_d-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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