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Crystal Lab › Prototype structures › Orthorhombic

Ag₇Ca₂

Orthorhombic · space group Cmcm (No. 63) · Pearson oC36

Symmetry elements and Wyckoff positions (interactive)

Ag₇Ca₂ in Cmcm

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

Unit cell

Lattice constants
a = 9.478 Å, b = 5.525 Å, c = 14.079 Å; α = 90.00°, β = 90.00°, γ = 90.00°
Cell volume
737.3 ų
Atoms in the conventional cell
36 (Ag 28, Ca 8)
Formula units Z
4
Pearson symbol
oC36 — orthorhombic, base-centred lattice, 36 atoms per conventional cell
Symmetry operations
16 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
Ag1Ag4c40.00000.82670.2500
Ca4Ca8f80.00000.32190.1147
Ag2Ag8g80.75090.57750.2500
Ag3Ag16h160.83470.82930.0765

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 36 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

A7B2_oC36_63_cgh_f-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oC36, then the space-group number 63, then the Wyckoff letters occupied by each element in turn (Ag: 4c; Ca: 8f; Ag: 8g; Ag: 16h). Two structures with the same label are the same arrangement with different cell parameters or coordinates.

Other compounds with this structure

Ag₇Yb₂ <!--beginning with an

Source

Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A7B2_oC36_63_cgh_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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