Oxidation of Pu alloys stabilized in δ–phase: Study of Ga alloying element behavior by using EXAFS analysis and Reverse Monte Carlo simulation

Ravat, B.; Favart, N.; Jolly, L.; Menut, Denis; Oudot, B.; Delaunay, F.; Popa, Iolanda Valentina; Chevalier, S.

doi:10.1016/j.corsci.2023.111144

Cited by 4 publications

(1 citation statement)

References 41 publications

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“…The P–T diagram for Pu oxides in dry air also exhibit the prevailing appearance of PuO 2 as the most-stable oxide in all the considered phase space (Figure e). This is fully consistent with the experimental observations on the oxidation behaviors of Pu metal at temperatures of 300–1000 K and pressures of 10 –9 ∼ 0.1 bar, ,− where it is PuO 2 on the top layer to contact with the environmental atmosphere. Another oxide Pu 2 O 3 only forms between the PuO 2 layer and metal substrate due to the insufficient O atoms there, and Pu 2 O 3 is also a favored composition that resides on the convex-hull line (i.e., free from spontaneous decomposition, see Figure c).…”

Section: Resultsmentioning

confidence: 99%

Environmental Stability of Actinide Oxides Mapped by Integrated and Accurate First-Principles Calculations

Sun,

Ye,

Zhang

et al. 2024

J. Phys. Chem. C

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The synthesis, storage, application, and disposal of various actinide materials in the fields of nuclear-fuel-based clean energy and actinide-metal-based metallurgy always closely correlate with the stabilities of U and Pu oxides in many atmospheric and aqueous environments. It is technologically important to jointly evaluate both the thermodynamic and electrochemical stabilities of actinide oxides there, for which free energy of formation (Δf G) is the key physical quantity. Due to various unavoidable technical and physical challenges in experiments, the Δf G data for these polyvalent oxides have long-standing inaccurate and incomplete problems. Here, we design an integrated first-principles approach to carry out efficient structural screenings, accurate energetic calculations by considering both the exact electronic potential and phononic contribution, and reliable mappings of the thermodynamic and electrochemical phase diagrams for anhydrous and hydrous actinide oxides in different environments (e.g., dry air, humid air, and aqueous solution). Based on the accurate and complete stability-composition-environment relationships constructed here, the established thermodynamic and electrochemical understandings can successfully explain versatile experimental observations on the hydration, oxidation, and corrosion behaviors of actinide oxides. Finally, the isotope effects on Δf G values are quantitatively predicted, revealing that any oxide will have nearly the same stability in environments with light and heavy waters. The systematically accurate electronic structure, thermodynamic stability, and electrochemical stability of actinide oxides as obtained in this work can provide many related theoretical and experimental studies in the future with reliable and desirable numerical references, as well as the comprehensively revealed physical and chemical mechanisms.

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Section: Resultsmentioning

confidence: 99%

Environmental Stability of Actinide Oxides Mapped by Integrated and Accurate First-Principles Calculations

Sun,

Ye,

Zhang

et al. 2024

J. Phys. Chem. C

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Characterization of δ-PuGa (1 at%. Ga) Oxidation Under Dry Oxygen Atmosphere Exposure

Favart,

Ravat,

Jolly

et al. 2024

High Temperature Corrosion of mater.

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The oxidation of δ-stabilized plutonium alloy was studied under dry oxygen exposures for temperatures varying from 100 up to 300 °C and oxygen partial pressures varying from 10–4 up to 500 mbar. The coupling of X-ray diffraction, Raman spectroscopy and FIB-SEM has allowed to show that the oxide scale is composed of an outer layer of PuO2 and an inner mixed layer of α + β-Pu2O3 platelets propagating into a metallic zone corresponding to the stable phase of unalloyed Pu. Furthermore, the analysis of Pu oxidation kinetics has displayed first a parabolic growth governed by the diffusion of interstitial oxygen. This step consists of the thickening of the Pu2O3 layer with a decrease in α-Pu2O3 ratio in favor of β-Pu2O3. Then, a second step occurs consisting of a linear growth of the PuO2-layer with the formation of thick nodules which tend to cover the whole oxide surface. Based on the results of this work, a general oxidation mechanism for δ-Pu alloy is provided.

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Uranium–plutonium–oxygen phase diagram: Investigating the solvus of fluorite's exsolution

Vauchy,

Hirooka,

Horii

et al. 2024

Journal of Nuclear Materials

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Oxidation of Pu alloys stabilized in δ–phase: Study of Ga alloying element behavior by using EXAFS analysis and Reverse Monte Carlo simulation

Cited by 4 publications

References 41 publications

Environmental Stability of Actinide Oxides Mapped by Integrated and Accurate First-Principles Calculations

Environmental Stability of Actinide Oxides Mapped by Integrated and Accurate First-Principles Calculations

Characterization of δ-PuGa (1 at%. Ga) Oxidation Under Dry Oxygen Atmosphere Exposure

Uranium–plutonium–oxygen phase diagram: Investigating the solvus of fluorite's exsolution

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