First principles study of oxygen diffusion in plutonium dioxide, sesquioxide, and their interface under activated conditions

The oxidation corrosion of metallic plutonium, intentional or unavoidable, is a crucial issue for its actual applications. However, the atomistic mechanisms behind such oxidation remain elusive. Through a systematic first principles study of the oxygen diffusion in plutonium dioxide, sesquioxide, and their interface, we obtained some dynamic parameters of oxygen diffusion in different oxides. Moreover, we also discovered a dynamic equilibrium and an anisotropic pathway that prefers the [001] crystallographic direction for oxygen diffusion at their interface. These conclusions were in accord with the experimental results of ceria oxides, an ideal analogue of the plutonium oxides with 4f electrons. These results help us to better understand the mechanisms of oxidation corrosion of plutonium at an atomistic level, and to reveal prospects for applications of the anisotropic orientation-relevant fluorite-structured oxides.