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

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

doi:10.1016/j.jnucmat.2018.04.046

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

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

Department of Applied Physics

Research output: Contribution to journal › Article › Scientific › peer-review

21 Citations (Scopus)

Abstract

The charge compensation mechanisms in U_yNd_1−yO_2±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 language	English
Pages (from-to)	145-150
Journal	Journal of Nuclear Materials
Volume	507
DOIs	https://doi.org/10.1016/j.jnucmat.2018.04.046
Publication status	Published - 15 Aug 2018
MoE publication type	A1 Journal article-refereed

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https://hal-cea.archives-ouvertes.fr/cea-02429995

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title = "New insight in the uranium valence state determination in UyNd1−yO2±x",

abstract = "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).",

author = "Rene Bes and Kristina Kvashnina and Andreas Rossberg and Gianinna Dottavio and Lionel Desgranges and Yves Pontillon and Solari, {Pier Lorenzo} and Sergei Butorin and Philippe Martin",

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doi = "10.1016/j.jnucmat.2018.04.046",

language = "English",

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T1 - New insight in the uranium valence state determination in UyNd1−yO2±x

AU - Bes, Rene

AU - Kvashnina, Kristina

AU - Rossberg, Andreas

AU - Dottavio, Gianinna

AU - Desgranges, Lionel

AU - Pontillon, Yves

AU - Solari, Pier Lorenzo

AU - Butorin, Sergei

AU - Martin, Philippe

PY - 2018/8/15

Y1 - 2018/8/15

N2 - 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).

AB - 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).

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DO - 10.1016/j.jnucmat.2018.04.046

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EP - 150

JO - Journal of Nuclear Materials

JF - Journal of Nuclear Materials

ER -

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

Abstract

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