Phase segregation in mixed Nb-Sb double perovskites Ba2LnNb1-xSbxO6
The phase composition of two series of mixed Nb5+-Sb5+ double perovskites formed between the pairs Ba2EuNbO6-Ba2PrSbO6 and Ba2NdSbO6-Ba2NdNbO6 have been studied using synchrotron X-ray powder diffraction methods. In both series extensive phase segregation is observed demonstrating limited solubility...
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| Médium: | Journal article |
| Jazyk: | English |
| Vydáno: |
2008
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| Shrnutí: | The phase composition of two series of mixed Nb5+-Sb5+ double perovskites formed between the pairs Ba2EuNbO6-Ba2PrSbO6 and Ba2NdSbO6-Ba2NdNbO6 have been studied using synchrotron X-ray powder diffraction methods. In both series extensive phase segregation is observed demonstrating limited solubility of Sb5+ in these Nb5+ 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 Ba2EuNbO6 and rhombohedral R over(3, -) Ba2EuNbO6 is presented. It is postulated that this phase segregation is a consequence of competing bonding requirements of the Nb5+ and Sb5+ cations associated with their electronic configurations. © 2007 Elsevier Inc. All rights reserved. |
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