First-principles study of point defects in U3Si2: effects on the mechanical and electronic properties

Abstract

In recent years, U₃Si₂ has been proposed as an alternative nuclear fuel material to uranium dioxide (UO₂) because of its intrinsically high uranium density and thermal conductivity. However, the operation environment in the nuclear reactor is complex and extreme, such as in-pile neutron irradiation, and thus it is necessary to explore the radiation response behavior of U₃Si₂ and the physical properties of its damaged states. In the present study, first-principles calculations based on density functional theory were carried out to investigate the mechanical and electronic properties of defective U₃Si₂. Our results showed that the defect stability in U₃Si₂, except its interstitial defects, is dependent on its chemical environment. When vacancy, antisite or interstitial defects are introduced into U₃Si₂, its elastic modulus are decreased and its ductility is enhanced. Although the presence of defects in U₃Si₂ does not change its metallic nature and the electron distribution in its Fermi level, their effect on the partial chemical bonding interaction is significant. This study suggests that under a radiation environment, the created defects in U₃Si₂ remarkably affect its mechanical and electronic properties.