Actinide and lanthanide dioxide lattice dilatation mechanisms with defect ingrowths

Abstract

The effects of irradiation-induced defects on the fluorite-structured dioxide materials were investigated in the literature and explained with complex physical phenomena. An interpretation that can simply explain their effects on the structure has not been put forward so far. However, in a recent atomistic simulation study, a specific defect was found to be directly responsible for the alpha-particle irradiated UO2 lattice dilatation, and there was a linear relationship between them. It was also determined that this linear equation has two different slopes at low and high defect concentrations. In this paper, it was found that these phenomenon were not specific to UO2 and applicable to all fluorite-structured actinide and lanthanide dioxides studied here (CmO2, AmO2, CeO2, UO2, NpO2, PuO2, ThO2). The findings provide clues to the existence of more general law. The results have the potential to lead to significant improvements, such as why different radiation types (alpha-particle, alpha-decay, fission) swell the lattice at different saturation levels.