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Crystal Lab › Prototype structures › Monoclinic

Er₂Si₂O₇

Monoclinic · space group P121/c1 (No. 14) · Pearson mP22

Symmetry elements and Wyckoff positions (interactive)

Er₂Si₂O₇ in P121/c1

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

Unit cell

Lattice constants
a = 4.683 Å, b = 10.790 Å, c = 5.556 Å; α = 90.00°, β = 96.00°, γ = 90.00°
Cell volume
279.2 ų
Atoms in the conventional cell
22 (O 14, Er 4, Si 4)
Formula units Z
2
Pearson symbol
mP22 — monoclinic, primitive lattice, 22 atoms per conventional cell
Symmetry operations
4 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
O2O2a20.00000.00000.0000
Er1Er4e40.38830.15070.5932
O3O4e40.70520.05140.3653
O4O4e40.62350.18090.9583
O5O4e40.11840.20160.2522
Si6Si4e40.86010.11290.1442

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 22 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

A2B7C2_mP22_14_e_a3e_e-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol mP22, then the space-group number 14, then the Wyckoff letters occupied by each element in turn (O: 2a; Er: 4e; O: 4e; O: 4e; O: 4e; Si: 4e). Two structures with the same label are the same arrangement with different cell parameters or coordinates.

Other compounds with this structure

Ho₂Si₂O₇, Y₂Si₂O₇ <!--beginning with an

Source

Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A2B7C2_mP22_14_e_a3e_e-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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