Defect formation and its effect on the thermodynamic properties of Pu2Zr2O7 pyrochlore: a first-principles study

In the past decades, pyrochlores, such as Gd2Zr2O7, have demonstrated great potential to immobilize nuclear wastes such as Pu, which results in the production of Pu2Zr2O7. Due to the high radioactivity of Pu, it is difficult to investigate the radiation response behavior of Pu2Zr2O7 and its physical properties of the damaged state experimentally. Consequently, few related data have been reported in the literature thus far. In this study, first-principles calculations have been carried out to investigate the defect formation and its effect on the thermodynamic properties of Pu2Zr2O7. It reveals that Pu-Zr antisite and O-8a interstitial defects are very easy to form in Pu2Zr2O7. In particular, the O-8a interstitial defect can be formed spontaneously, while it is mechanically unstable. When vacancy, interstitial or antisite defects are formed in Pu2Zr2O7, and the elastic moduli and Debye temperature are decreased. Besides, better ductility is resulted. As compared with other zirconate pyrochlores, such as Gd2Zr2O7, the Pu2Zr2O7 is suggested to be less resistant to radiation-induced amorphization. This study demonstrates that the created defects due to self-radiation from actinide decay have remarkable influences on the thermophysical properties of Pu2Zr2O7.

Automated summary

First-principles calculations were used to investigate defect formation and its effect on the thermodynamic properties of Pu2Zr2O7. The study found that Pu-Zr antisite and O-8a interstitial defects are easily formed in Pu2Zr2O7, decreasing elastic moduli and Debye temperature, while increasing ductility. Compared to other zirconate pyrochlores, Pu2Zr2O7 is suggested to be less resistant to radiation-induced amorphization. The study highlights the significant influence of defects created by self-radiation on the thermophysical properties of Pu2Zr2O7.