Crystal Lab › Prototype structures › Orthorhombic
Ca₃Ti₂O₇
Orthorhombic · space group Cmc21 (No. 36) · Pearson oC48
Symmetry elements and Wyckoff positions (interactive)
Ca₃Ti₂O₇ in Cmc21
SettingUnit cell
- Lattice constants
- a = 19.517 Å, b = 5.417 Å, c = 5.423 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 573.4 ų
- Atoms in the conventional cell
- 48 (Ca 12, O 28, Ti 8)
- Formula units Z
- 4
- Pearson symbol
- oC48 — orthorhombic, base-centred lattice, 48 atoms per conventional cell
- Symmetry operations
- 8 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Ca1 | Ca | 4a | 4 | 0.0000 | 0.7483 | 0.0290 |
| O3 | O | 4a | 4 | 0.0000 | 0.1876 | 0.9868 |
| Ca2 | Ca | 8b | 8 | 0.6876 | 0.7590 | 0.4747 |
| O4 | O | 8b | 8 | 0.6972 | 0.8042 | 0.0132 |
| O5 | O | 8b | 8 | 0.5860 | 0.9622 | 0.2883 |
| O6 | O | 8b | 8 | 0.6099 | 0.4622 | 0.2117 |
| Ti7 | Ti | 8b | 8 | 0.5989 | 0.2509 | 0.5000 |
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 8 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
A3B7C2_oC48_36_ab_a3b_b-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 36, then the Wyckoff letters occupied by each element in turn (Ca: 4a; O: 4a; Ca: 8b; O: 8b; O: 8b; O: 8b; Ti: 8b). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Other compounds with this structure
Bi₃Mn₂O₇, Ca₃Mn₂O₇, Ca₃Ru₂O₇, Ca₃Ti₂O₇, Mg₃Ti₂O₇, Sr₃Sn₂O₇, Sr₃Zr₂O₇ <!--beginning with an
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A3B7C2_oC48_36_ab_a3b_b-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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