A first principles investigation of defect energetics and diffusion in actinide dioxides

In this work, we have studied the formation and migration of various neutral intrinsic defects in AnO2. The nonstoichiometric defects such as vacancy defect, interstitial defect, and antisite defect as well as stoichiometric defects such as Schottky defect and Frenkel pairs has been considered for investigation. The formation energies of point defects are much higher in ThO2 as compared to UO2 and PuO2. The binding energy of defect clusters indicate that formation of Frenkel pair and Schottky defect is favorable over individual defects in ThO2. In case of UO2 and PuO2, hyper-stoichiometric defects are more stable than hypo-stoichiometric defects. The results obtained in this work are in good agreement with experimental results.