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

✍ Scribed by E.H.P. Cordfunke; A.S. Booij; V. Smit-Groen; P. van Vlaanderen; D.J.W. IJdo

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 333 KB
• Volume: 131
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1997.7392

✦ Synopsis

The perovskite-type BaUO 3 structure has been investigated by X-ray and neutron diffraction. The Ba/U ratio, the (Ba, Sr)/U ratio, and the oxygen stoichiometry in Ba 1؉y UO 3؉x were 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 BaUO 3 -Ba 1؉y UO 3؉x -Ba 3 UO 6 exists in which uranium vacancies are gradually filled with barium ions whereas uranium is oxidized via the pentavalent to the hexavalent state in Ba 3 UO 6 (‫؍‬Ba 2 (Ba, U)O 6 ).