On the O-rich domain of the U-Am-O phase diagram - Archive ouverte HAL Access content directly
Journal Articles Journal of Nuclear Materials Year : 2020

## On the O-rich domain of the U-Am-O phase diagram

(1, 2) , (1, 2) , (3, 2) , (3, 2) , (3, 2) , (4) , (5, 2) , (3, 2) , (3, 2)
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E. Epifano
• Function : Correspondent author
• PersonId : 1129716

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Romain Vauchy
Florent Lebreton
Andreas C. Scheinost
• Function : Author
• PersonId : 922571
P.M. Martin

#### Abstract

Uranium–Americium oxides U$_{1−y}$Am$_y$O$_{2±x}$ are promising candidates as possible transmutation targets for next generation nuclear reactors. In the context of a comprehensive investigation of their thermodynamic and thermal properties, the behaviour in oxidizing conditions is here studied. In a recent work, the behaviour in air of stoichiometric and sub-stoichiometric U$_{1−y}$Am$_y$O$_{2±x}$ compounds, with various Am content, was investigated by high-temperature X-ray Diffraction. Herein, the hyper-stoichiometric oxides obtained from that study are investigated by X-ray Absorption Spectroscopy. The new data, together with the previous XRD results, allow determining the exact compositions of the samples and hence obtaining phase diagram points in the O-rich domain of the U-Am-O system. Indeed, five phase diagram points at 1473 K are obtained: two tie-lines in the M$_4$O${9-}$M$_3$O$_8$ domain, for Am/(Am + U) = 0.10 and 0.15, one tie line in the MO$_{2+x-}$M$_3$O$_8$ domain, for Am/(Am + U) = 0.28, and two points in the single phase MO$_{2±x}$ domain, for higher americium concentration. From these data, it is also concluded that trivalent americium has a small solubility in the M$_4$O$_9$ and M$_3$O$_8$ phases.

### Dates and versions

cea-02529003 , version 1 (07-03-2022)

### Licence

Attribution - NonCommercial - CC BY 4.0

### Identifiers

• HAL Id : cea-02529003 , version 1
• DOI :
• PII :

### Cite

E. Epifano, Romain Vauchy, Florent Lebreton, R. Lauwerier, A. Joly, et al.. On the O-rich domain of the U-Am-O phase diagram. Journal of Nuclear Materials, 2020, 531, pp.151986. ⟨10.1016/j.jnucmat.2020.151986⟩. ⟨cea-02529003⟩

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