paper

The environmental dependence of redox energetics of PuO2 and Î±-Pu2O3: A quantitative solution from DFT+U calculations

arXiv:1208.3745 · doi:10.1016/j.physleta.2012.07.030

Abstract

We report a comprehensive density functional theory (DFT) + $U$ study of the energetics of charged and neutral oxygen defects in both PuO $_{2}$ and $I^\pm$ -Pu $_{2}$ O $_{3}$ , and present a quantitative determination of the equilibrium compositions of reduced PuO $_{2}$ (PuO $_{2 - x}$ ) as functions of environmental temperature and partial pressure of oxygen, which shows fairly agreement with corresponding high-temperature experiments. Under ambient conditions, the endothermic reduction of PuO $_{2}$ to $I^\pm$ -Pu $_{2}$ O $_{3}$ is found to be facilitated by accompanying volume expansion of PuO $_{2 - x}$ and the possible migration of O-vacancy, whereas further reduction of $I^\pm$ -Pu $_{2}$ O $_{3}$ is predicted to be much more difficult. In contrast to the endothermic oxidation of PuO $_{2}$ ,\ the oxidation of $I^\pm$ -Pu $_{2}$ O $_{3}$ is a stable exothermic process.

5 PLA pages, 4 figures