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Local structure and oxidation state of uranium in some ternary oxides: X-ray absorption analysis

Soldatov, A. V.; Lamoen, D.; Konstantinovic, M. J.; van den Berghe, S.; Scheinost, A. C.; Verwerft, M.

We investigated the local atomic and electronic structures of two related systematic sets of ternary uranium oxides, NaUO3 - KUO3 - RbUO3 and BaUO3 - Ba2U2O7 - BaUO4, by measuring the X-ray absorption near edge structure (XANES). The results are compared with calculations based on self-consistent real space full multiple scattering analysis. We found a very good agreement between measured and calculated spectra, which indicates that the uranium ions are in pure U5+ oxidation state in these compounds. The low energy shoulder observed in the U L3 edge XANES is an intrinsic feature of the uranium unoccupied 3d electronic state of the U5+ ions. Specific double shoulder features in the higher energy range of the U L3 edge XANES can be interpreted as indicative of the pure cubic perovskite structure.

Keywords: XAFS; XANES; uranium; ternary uranium oxides; oxidation state; pentavalent

  • Journal of Solid State Chemistry 180(2007), 53-60

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Publ.-Id: 8341