Impacts of Am Aggregation on the Bulk Properties of Mixed Oxides (U, Am)O<sub>2</sub> from First Principles

We present a first-principles density functional theory with the Coulomb interaction <i>U</i> (DFT + <i>U</i>) investigation of the bulk properties, including structural, energetic, electronic, and mechanical properties for uranium–americium mixed oxides (U, Am)O<sub>2&...

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Bibliographic Details
Main Authors: Tao Liu, Ziyi Yang, Xiaoyan Yu, Tao Gao
Format: Article
Language:English
Published: MDPI AG 2024-11-01
Series:Physics
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Online Access:https://www.mdpi.com/2624-8174/6/4/76
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Summary:We present a first-principles density functional theory with the Coulomb interaction <i>U</i> (DFT + <i>U</i>) investigation of the bulk properties, including structural, energetic, electronic, and mechanical properties for uranium–americium mixed oxides (U, Am)O<sub>2</sub>. The various Am aggregation contents were investigated to better understand the impact of Am on the nuclear fuel UO<sub>2</sub>. The supercell defect models at different scales were used to describe the solid solution (U, Am)O<sub>2</sub>. The obtained results show that different contents of Am aggregation have a significant impact on the volume and energy of the formation of mixed oxide systems. The results of the electronic structure calculations exhibit no bandgap owing to the mixing of UO<sub>2</sub> and AmO<sub>2</sub>. The mixing enthalpy of the Am aggregation systems is used to describe the phase stability of the solid solution. In particular, the mixing enthalpy of (U, Am)O<sub>2</sub> is significantly reduced as the Am content increases. The elastic properties of the (U, Am)O<sub>2</sub> mixed oxides have also been compared as a function of the Am content. Moreover, the impacts of the whole Pu aggregation content range on the bulk properties for the (U, Pu)O<sub>2</sub> mixed oxides are also discussed.
ISSN:2624-8174