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Crystal Lab › Prototype structures › Orthorhombic

LaCa₂Mn₂O₇

Orthorhombic · space group Cmcm (No. 63) · Pearson oC48

Symmetry elements and Wyckoff positions (interactive)

LaCa₂Mn₂O₇ in Cmcm

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

Unit cell

Lattice constants
a = 19.202 Å, b = 5.456 Å, c = 5.415 Å; α = 90.00°, β = 90.00°, γ = 90.00°
Cell volume
567.3 ų
Atoms in the conventional cell
48 (La 4, O 28, Ca 8, Mn 8)
Formula units Z
4
Pearson symbol
oC48 — orthorhombic, base-centred lattice, 48 atoms per conventional cell
Symmetry operations
16 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
La2La4c40.00000.25030.2500
O4O4c40.00000.69860.2500
O5O8e80.39280.00000.0000
O6O8e80.08830.00000.0000
Ca1Ca8g80.31560.73480.2500
Mn3Mn8g80.39970.25000.2500
O7O8g80.30130.29060.2500

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 48 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

A2BC2D7_oC48_63_g_c_g_c2eg-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oC48, then the space-group number 63, then the Wyckoff letters occupied by each element in turn (La: 4c; O: 4c; O: 8e; O: 8e; Ca: 8g; Mn: 8g; O: 8g). Two structures with the same label are the same arrangement with different cell parameters or coordinates.

Other compounds with this structure

BaEu₂Mn₂O₇, LaRb₂Mn₂O₇, PrCa₂Mn₂O₇, SrGd₂Co₂O₇ <!--beginning with an

Source

Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A2BC2D7_oC48_63_g_c_g_c2eg-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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