First-principles study of point defects in U 3 Si 2 : effects on the mechanical and electronic properties.

In recent years, U 3 Si 2 has been proposed as an alternative nuclear fuel material to uranium dioxide (UO 2 ) 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 U 3 Si 2 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 U 3 Si 2 . Our results showed that the defect stability in U 3 Si 2 , except its interstitial defects, is dependent on its chemical environment. When vacancy, antisite or interstitial defects are introduced into U 3 Si 2 , its elastic modulus are decreased and its ductility is enhanced. Although the presence of defects in U 3 Si 2 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 U 3 Si 2 remarkably affect its mechanical and electronic properties.