Tilting and distortion in rutile-related mixed metal ternary uranium oxides: a structural, spectroscopic, and theoretical investigation

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dc.contributor.authorMurphy, GLen_AU
dc.contributor.authorZhang, Zen_AU
dc.contributor.authorTesch, Ren_AU
dc.contributor.authorKowalski, PMen_AU
dc.contributor.authorAvdeev, Men_AU
dc.contributor.authorKuo, EYen_AU
dc.contributor.authorGregg, DJen_AU
dc.contributor.authorKegler, Pen_AU
dc.contributor.authorAlekseev, EVen_AU
dc.contributor.authorKennedy, BJen_AU
dc.date.accessioned2021-09-13T22:03:38Zen_AU
dc.date.available2021-09-13T22:03:38Zen_AU
dc.date.issued2021-01-29en_AU
dc.date.statistics2021-09-13en_AU
dc.description.abstractA systematic investigation examining the origins of structural distortions in rutile-related ternary uranium AUO4 oxides using a combination of high-resolution structural and spectroscopic measurements supported by ab initio calculations is presented. The structures of β-CdUO4, MnUO4, CoUO4, and MgUO4 are determined at high precision by using a combination of neutron powder diffraction (NPD) and synchrotron X-ray powder diffraction (S-XRD) or single crystal X-ray diffraction. The structure of β-CdUO4 is best described by space group Cmmm whereas MnUO4, CoUO4, and MgUO4 are described by the lower symmetry Ibmm space group and are isostructural with the previously reported β-NiUO4 [Murphy et al. Inorg. Chem.2018, 57, 13847]. X-ray absorption spectroscopy (XAS) analysis shows all five oxides contain hexavalent uranium. The difference in space group can be understood on the basis of size mismatch between the A2+ and U6+ cations whereby unsatisfactory matching results in structural distortions manifested through tilting of the AO6 polyhedra, leading to a change in symmetry from Cmmm to Ibmm. Such tilts are absent in the Cmmm structure. Heating the Ibmm AUO4 oxides results in reduction of the tilt angle. This is demonstrated for MnUO4 where in situ S-XRD measurements reveal a second-order phase transition to Cmmm near T = 200 °C. Based on the extrapolation of variable temperature in situ S-XRD data, CoUO4 is predicted to undergo a continuous phase transition to Cmmm at ∼1475 °C. Comparison of the measured and computed data highlights inadequacies in the DFT+U approach, and the conducted analysis should guide future improvements in computational methods. The results of this investigation are discussed in the context of the wider AUO4 family of oxides. © 2021 American Chemical Societyen_AU
dc.identifier.citationMurphy, G. L., Zhang, Z., Tesch, R., Kowalski, P. M., Avdeev, M., Kuo, E. Y., Gregg, D. J., Kegler, P., Alekseev, E. V., & Kennedy, B. J. (2021). Tilting and distortion in rutile-related mixed metal ternary uranium oxides: a structural, spectroscopic, and theoretical investigation. Inorganic Chemistry, 60(4), 2246–2260. doi:10.1021/acs.inorgchem.0c03077en_AU
dc.identifier.issn1520-510Xen_AU
dc.identifier.issue4en_AU
dc.identifier.journaltitleInorganic Chemistryen_AU
dc.identifier.pagination2246-2260en_AU
dc.identifier.urihttps://doi.org/10.1021/acs.inorgchem.0c03077en_AU
dc.identifier.urihttps://apo.ansto.gov.au/dspace/handle/10238/11679en_AU
dc.identifier.volume60en_AU
dc.language.isoenen_AU
dc.publisherAmerican Chemical Societyen_AU
dc.subjectOxidesen_AU
dc.subjectCationsen_AU
dc.subjectCrystal structureen_AU
dc.subjectNeutron diffractionen_AU
dc.subjectX-ray diffractionen_AU
dc.subjectPhase transformationsen_AU
dc.titleTilting and distortion in rutile-related mixed metal ternary uranium oxides: a structural, spectroscopic, and theoretical investigationen_AU
dc.typeJournal Articleen_AU
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