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Title: Nonstoichiometry in strontium uranium oxide: understanding the rhombohedral–orthorhombic transition in SrUO4
Authors: Murphy, GL
Kennedy, BJ
Kimpton, JA
Gu, QF
Johannessen, B
Beridze, G
Kowalski, PM
Bosbach, D
Avdeev, M
Zhang, Z
Keywords: Phase transformations
Crystal defects
X-ray diffraction
Neutron diffraction
Issue Date: 29-Aug-2016
Publisher: American Chemical Society
Citation: Murphy, G. L., Kennedy, B. J., Kimpton, J. A., Gu, Q., Johannessen, B., Beridze, G., Kowalski, P. M., Bosbach, D., Avdeev, M., & Zhang, Z. (2016). Nonstoichiometry in strontium uranium oxide: understanding the rhombohedral–orthorhombic transition in SrUO4. Inorganic Chemistry, 55(18), 9329–9334. doi:10.1021/acs.inorgchem.6b01391
Abstract: In situ neutron and synchrotron X-ray diffraction studies demonstrate that SrUO4 acts as an oxygen transfer agent, forming oxygen vacancies under both oxidizing and reducing conditions. Two polymorphs of SrUO4 are stable at room temperature, and the transformation between these is observed to be associated with thermally regulated diffusion of oxygen ions, with partial reduction of the U6+ playing a role in both the formation of oxygen deficient α-SrUO4−δ and its subsequent transformation to stoichiometric β-SrUO4. This is supported by ab initio calculations using density functional theory calculations. The oxygen vacancies play a critical role in the first order transition that SrUO4 undergoes near 830 °C. The changes in the oxidation states and U geometry associated with the structural phase transition have been characterized using X-ray absorption spectroscopy, synchrotron X-ray diffraction, and neutron diffraction. © 2016 American Chemical Society
ISSN: 1520-510X
Appears in Collections:Journal Articles

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