Towards a generalized vision of oxides: disclosing the role of cations and anions in determining unit-cell dimensions

Theoretical calculations of the electron‐localization function show that, at the volumes of the two CaO phases (rocksalt and CsCl type), the parent Ca structures (fcc: face‐centred cubic and sc: simple cubic, respectively) exhibit charge concentration zones which coincide with the positions occupied...

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Bibliographic Details
Published in:Acta crystallographica. Section B, Structural science Structural science, 2010-06, Vol.66 (3), p.338-344
Main Authors: Vegas, Ángel, Mattesini, Maurizio
Format: Article
Language:English
Subjects:
Atomic structure
Barium stannate
Calcium fluoride
Cations
Cells
Charge
electron localization
high-pressure experiments
Mathematical analysis
Oxidation
Oxides
Phases
Research Papers
Theory
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Summary:Theoretical calculations of the electron‐localization function show that, at the volumes of the two CaO phases (rocksalt and CsCl type), the parent Ca structures (fcc: face‐centred cubic and sc: simple cubic, respectively) exhibit charge concentration zones which coincide with the positions occupied by the O atoms in their oxides. Similar features, also observed for the pairs Ca/CaF2 and BaSn/BaSnO3, are supported by recent high‐pressure experiments as well as electron‐localization function (ELF) calculations, carried out on elemental K. At very high pressures, the elemental K adopts the hP4 structure, topologically identical to that of the K atoms in high‐pressure K2S and high‐temperature α‐K2SO4. Moreover, the ELF for the hP4 structure shows charge concentration (∼ 2 electrons) at the sites occupied by the S atoms in the high‐pressure K2S phase. All these features confirm the oxidation/high‐pressure equivalence as well as the prediction of how cation arrays should be metastable phases of the parent metals. For the first time to our knowledge, the structure type, dimension and topology of several oxides and fluorides (CaO, CaF2 and BaSnO3) are explained in univocal physical terms.
ISSN:0108-7681
2052-5192
1600-5740
2052-5206
DOI:10.1107/S0108768110013200