Structural and Thermodynamic Characterization of the Perovskite-Related Ba1+yUO3+xand (Ba, Sr)1+yUO3+xPhases

The perovskite-type BaUO3structure has been investigated by X-ray and neutron diffraction. The Ba/U ratio, the (Ba, Sr)/U ratio, and the oxygen stoichiometry in Ba1+yUO3+xwere varied, and the integral enthalpies of formation were determined by solution calorimetry. In addition, equilibrium oxygen pa...

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Bibliographic Details
Published in:Journal of solid state chemistry 1997-07, Vol.131 (2), p.341-349
Main Authors: Cordfunke, E.H.P., Booij, A.S., Smit-Groen, V., van Vlaanderen, P., IJdo, D.J.W.
Format: Article
Language:English
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Summary:The perovskite-type BaUO3structure has been investigated by X-ray and neutron diffraction. The Ba/U ratio, the (Ba, Sr)/U ratio, and the oxygen stoichiometry in Ba1+yUO3+xwere varied, and the integral enthalpies of formation were determined by solution calorimetry. In addition, equilibrium oxygen partial pressures were measured using a reversible EMF cell. The chemical defect mechanism is discussed, and it is shown that the continuous series BaUO3–Ba1+yUO3+x–Ba3UO6exists in which uranium vacancies are gradually filled with barium ions whereas uranium is oxidized via the pentavalent to the hexavalent state in Ba3UO6(=Ba2(Ba,U)O6).
ISSN:0022-4596
1095-726X
DOI:10.1006/jssc.1997.7392