New insight in the uranium valence state determination in UyNd1−yO2±x

Research output: Contribution to journalArticleScientificpeer-review


  • Rene Bes
  • Kristina Kvashnina
  • Andreas Rossberg
  • Gianinna Dottavio
  • Lionel Desgranges
  • Yves Pontillon
  • Pier Lorenzo Solari
  • Sergei Butorin
  • Philippe Martin

Research units

  • Helmholtz-Zentrum Dresden Rossendorf
  • CEA
  • Synchrotron Soleil
  • Department of Physics and Astronomy


The charge compensation mechanisms in UyNd1−yO2±x and its consequence on the overall O stoichiometry (or O/M ratio where M = Nd + U) have been studied through the uranium valence state mixture evolution as a function of Nd content up to y = 0.62 by means of high energy resolution fluorescence detection X-ray absorption spectroscopy (HERFD-XAS) at the U M4-edge. Our results clearly demonstrate the formation of U5+ at low Nd content (y 0.15). Upon increasing the Nd content, oxygen vacancies and the formation of U6+ appear as competing mechanisms for intermediate Nd concentrations, leading to the co-existence of U4+/U5+/U6+ mixed valence and an overall hypostoichiometry (O/M 2.00). Finally, the formation of U6+ associated with strongly distorted U local environment is observed for high Nd concentrations (y = 0.62), leading to an overall hyperstoichiometry (O/M 2.00).


Original languageEnglish
Pages (from-to)145-150
JournalJournal of Nuclear Materials
Publication statusPublished - 15 Aug 2018
MoE publication typeA1 Journal article-refereed

ID: 20820263