The influence of atomic delocalization on dynamic behavior in Ce-Ni metallic melts

Abstract

In Ce-Ni melts, the atomic self-diffusion coefficient decreasing nonlinearly as the Ce content decrease is observed via the ab initio molecular dynamics simulation. A mutation appears in the self-diffusion coefficient curve when the Ce content is <33% (=Ce1Ni2). By analysing the topologic and electronic structures, this dynamic mutation is caused by the delocalization of Ce-4f electron. For Ce atom with high localized degree, the electron exchange with Ni atoms is soft. It is easy to form unstable polyhedra with coordination number between 13 and 14, which leads to faster dynamic behavior. On the contrary, Ce atom with low localized degree has slower dynamic behavior. These two types of Ce atoms vary in volume greatly and affect the atomic stacking effect. In Ce-rich and Ni-rich melts, the self-diffusion coefficient changes visibly due to the change of stacking effect. The localization degree of 4f-electron depending on composition changes are rarely observed in binary melts. This provides a good model for the further study of the electronic structures, magnetic and dynamic behavior of Ce-based melts.