Phase segregation in mixed Nb-Sb double perovskites Ba{sub 2}LnNb{sub 1-x}Sb{sub x}O{sub 6}

Journal Article · Fri Feb 15 04:00:00 EST 2008 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2007.11.035· OSTI ID:21043891

Saines, Paul J ^[1]

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1. School of Chemistry, University of Sydney, Sydney, NSW 2006 (Australia)

The phase composition of two series of mixed Nb{sup 5+}-Sb{sup 5+} double perovskites formed between the pairs Ba{sub 2}EuNbO{sub 6}-Ba{sub 2}PrSbO{sub 6} and Ba{sub 2}NdSbO{sub 6}-Ba{sub 2}NdNbO{sub 6} have been studied using synchrotron X-ray powder diffraction methods. In both series extensive phase segregation is observed demonstrating limited solubility of Sb{sup 5+} in these Nb{sup 5+} perovskites, irrespective of the precise structures of the double perovskite. Evidence for a monoclinic I2/m phase in the series formed between tetragonal I4/m Ba{sub 2}EuNbO{sub 6} and rhombohedral R3-bar Ba{sub 2}EuNbO{sub 6} is presented. It is postulated that this phase segregation is a consequence of competing bonding requirements of the Nb{sup 5+} and Sb{sup 5+} cations associated with their electronic configurations. - Graphical abstract: The incompatibility of Sb and Nb in single-phase perovskites is explored for two families of oxides, namely Ba{sub 2}EuNbO{sub 6}-Ba{sub 2}PrSbO{sub 6} and Ba{sub 2}NdSbO{sub 6}-Ba{sub 2}NdNbO{sub 6}. Limited solubility of Sb{sup 5+} in these Nb{sup 5+} perovskites is observed, irrespective of their precise structure. This is apparently a consequence of competing bonding requirements of the Nb{sup 5+} and Sb{sup 5+} cations.

• OSTI ID: 21043891
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 2 Vol. 181; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ANTIMONY COMPOUNDS
ANTIMONY IONS
BARIUM COMPOUNDS
ELECTRONIC STRUCTURE
EUROPIUM COMPOUNDS
MONOCLINIC LATTICES
NEODYMIUM COMPOUNDS
NIOBIUM COMPOUNDS
NIOBIUM IONS
OXIDES
PEROVSKITE
PRASEODYMIUM COMPOUNDS
SEGREGATION
SYNCHROTRONS
TETRAGONAL LATTICES
X-RAY DIFFRACTION