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Crystal Lab › Prototype structures › Orthorhombic

alpha_{L}'-Ca₂SiO₄ Ca₂O₄Si

Orthorhombic · space group Pna21 (No. 33) · Pearson oP84

Symmetry elements and Wyckoff positions (interactive)

alpha_{L}'-Ca₂SiO₄ in Pna21

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

Unit cell

Lattice constants
a = 20.527 Å, b = 9.496 Å, c = 5.590 Å; α = 90.00°, β = 90.00°, γ = 90.00°
Cell volume
1089.6 ų
Atoms in the conventional cell
84 (Ca 24, O 48, Si 12)
Formula units Z
12
Pearson symbol
oP84 — orthorhombic, primitive lattice, 84 atoms per conventional cell
Symmetry operations
4 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
Ca1Ca4a40.77870.07260.7465
Ca2Ca4a40.44170.04690.8011
Ca3Ca4a40.12250.07940.7025
Ca4Ca4a40.99580.81370.7228
Ca5Ca4a40.66270.78360.7652
Ca6Ca4a40.32750.80010.7453
O10O4a40.66280.92870.2032
O11O4a40.60800.43320.1838
O12O4a40.58450.69980.0427
O13O4a40.49880.56100.2906
O14O4a40.59690.67340.4786
O15O4a40.95000.44620.1919
O16O4a40.92520.69030.0127
O17O4a40.92130.68810.4742
O18O4a40.83440.54950.1618
O7O4a40.75850.85040.4906
O8O4a40.77160.86740.0053
O9O4a40.78110.06400.2141
Si19Si4a40.26070.06800.7592
Si20Si4a40.92840.08050.7557
Si21Si4a40.58960.09590.7296

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 84 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

A2B4C_oP84_33_6a_12a_3a-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oP84, then the space-group number 33, then the Wyckoff letters occupied by each element in turn (Ca: 4a; Ca: 4a; Ca: 4a; Ca: 4a; Ca: 4a; Ca: 4a; O: 4a; O: 4a; O: 4a; O: 4a; O: 4a; O: 4a; O: 4a; O: 4a; O: 4a; O: 4a; O: 4a; O: 4a; Si: 4a; Si: 4a; Si: 4a). Two structures with the same label are the same arrangement with different cell parameters or coordinates.

Note: \alpha_{L}'-Ca₂SiO₄.

Source

Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A2B4C_oP84_33_6a_12a_3a-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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