Influence of Phase Separation on the Oxidation of (U,Pu)O 2– x

Abstract : The oxidation of six (U1–y,Puy)O2–x powdered samples, with y = 14, 24, 35, 46, 54, and 62 mol %, was studied in situ by high-temperature XRD at different temperatures. The samples were first reduced at 1500 °C to an oxygen to metal ratio (O/M) lower than 2.00. Afterward, the temperature was rapidly decreased to a value between 200 and 800 °C, which was followed by a long isothermal plateau during which diffraction patterns were recorded continuously. We observed structural changes in the material as it oxidized, in some cases passing through a biphasic domain. We discuss the influence of phase separation on the formation of a passive layer and the kinetics of phase transformations. It was found that entering the biphasic fcc1 + fcc2 domain will inhibit the formation of a passive layer. We hypothesize that the reason behind this behavior is the dependence of oxygen diffusion on the concentration of oxygen defects
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Journal of Physical Chemistry C, American Chemical Society, 2015, 119 (40), pp.23159 - 23167. 〈10.1021/acs.jpcc.5b07407〉
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Contributeur : Laure-Hélène Davoine <>
Soumis le : jeudi 14 juin 2018 - 15:29:54
Dernière modification le : lundi 29 octobre 2018 - 14:34:18

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Michal Strach, Renaud Belin, Jean-Christophe Richaud, Jacques Rogez. Influence of Phase Separation on the Oxidation of (U,Pu)O 2– x. Journal of Physical Chemistry C, American Chemical Society, 2015, 119 (40), pp.23159 - 23167. 〈10.1021/acs.jpcc.5b07407〉. 〈hal-01815807〉

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