Diffusion in undoped and Cr-doped amorphous UO2

Owen, Megan W.; Cooper, M.W.D.; Rushton, Michael; Claisse, Antoine; Lee, William; Middleburgh, Simon C.

doi:10.1016/j.jnucmat.2023.154270

Cited by 3 publications

(1 citation statement)

References 49 publications

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“…In addition, Miao et al investigated the response of U 3 Si 2 to 84 MeV Xe ion irradiation at 600 • C and found that the U 3 Si 2 is strongly resistant to radiation-induced amorphization [29]. Theoretically, Owen studied amorphous UO 2 systems using classical molecular dynamics methods and reported that the amorphous structure of UO 2 , i.e., oxygen ions, are coordinated with 3.65 uranium ions and uranium ions are coordinated with 7.31 oxygen ions [6]. Moreover, ab initio molecular dynamics (AIMD) computer simulations of low-energy recoil events in UO 2 and ThO 2 were carried out by Xiao et al, who determined the threshold displacement energies and revealed a number of novel point defects [30,31].…”

Section: Introductionmentioning

confidence: 99%

Ab Initio Molecular Dynamics Study of Electron Excitation Effects on UO2 and U3Si

Jin,

Zhao,

Xiao

2023

Materials

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In this study, an ab initio molecular dynamics method is employed to investigate how the microstructures of UO2 and U3Si evolve under electron excitation. It is found that the U3Si is more resistant to electron excitation than UO2 at room temperature. UO2 undergoes a crystalline-to-amorphous structural transition with an electronic excitation concentration of 3.6%, whereas U3Si maintains a crystalline structure until an electronic excitation concentration reaches up to 6%. Such discrepancy is mainly due to their different electronic structures. For insulator UO2, once valence U 5f electrons receive enough energy, they are excited to the conduction bands, which induces charge redistribution. Anion disordering is then driven by cation disordering, eventually resulting in structural amorphization. As for metallic U3Si, the U 5f electrons are relatively more difficult to excite, and the electron excitation leads to cation disordering, which eventually drives the crystalline-to-amorphous phase transition. This study reveals that U3Si is more resistant to electron excitation than UO2 under an irradiation environment, which may advance the understanding of related experimental and theoretical investigations to design radiation-resistant nuclear fuel uranium materials.

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