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Crystal Lab › Prototype structures › Orthorhombic

Nd₂Si₂O₇

Orthorhombic · space group P212121 (No. 19) · Pearson oP44

Symmetry elements and Wyckoff positions (interactive)

Nd₂Si₂O₇ in P212121

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

Unit cell

Lattice constants
a = 5.394 Å, b = 12.950 Å, c = 8.720 Å; α = 90.00°, β = 90.00°, γ = 90.00°
Cell volume
609.1 ų
Atoms in the conventional cell
44 (Nd 8, O 28, Si 8)
Formula units Z
4
Pearson symbol
oP44 — orthorhombic, primitive lattice, 44 atoms per conventional cell
Symmetry operations
4 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
Nd1Nd4a40.99740.23140.4432
Nd2Nd4a40.50720.40960.6462
O3O4a40.47100.43400.1758
O4O4a40.25000.25930.1696
O5O4a40.72320.24870.2325
O6O4a40.39470.33010.4291
O7O4a40.25340.42050.8930
O8O4a40.73020.44850.9074
O9O4a40.39700.59410.9950
Si10Si4a40.47700.32180.2494
Si11Si4a40.47670.47480.9982

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 44 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_oP44_19_2a_7a_2a-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oP44, then the space-group number 19, then the Wyckoff letters occupied by each element in turn (Nd: 4a; Nd: 4a; O: 4a; O: 4a; O: 4a; O: 4a; O: 4a; O: 4a; O: 4a; Si: 4a; Si: 4a). Two structures with the same label are the same arrangement with different cell parameters or coordinates.

Other compounds with this structure

Ce₂Si₂O₇, Eu₂Si₂O₇, La₂Si₂O₇, Sm₂Si₂O₇ <!--beginning with an

Source

Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A2B7C2_oP44_19_2a_7a_2a-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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