A Comparative Study of Electron Radiation Responses of Pu₂Zr₂O₇ and La₂Zr₂O₇: An abinitio Molecular Dynamics Study

In this study, the response of Pu₂Zr₂O₇ and La₂Zr₂O₇ to electronic radiation is simulated, employing an ab initio molecular dynamics method. It is shown that Pu₂Zr₂O₇ undergoes a crystalline-to-amorphous structural transition with 0.3% electronic excitation, while for La₂Zr₂O₇, the structural amorphization occurs with 1.2% electronic excitation. During the microstructural evolution, the anion disorder further drives cation disorder and eventually results in the structural amorphization of Pu₂Zr₂O₇ and La₂Zr₂O₇. The difference in responses to electron radiation between Pu₂Zr₂O₇ and La₂Zr₂O₇ mainly results from the strong correlation effects between Pu 5f electrons and the smaller band gap of Pu₂Zr₂O₇. These results suggest that Pu₂Zr₂O₇ is less resistant to amorphization under local ionization rates that produce a low level of electronic excitation, since the level of the concentration of excited electrons is relatively low in Pu₂Zr₂O₇. The presented results will advance the understanding of the radiation damage effects of zirconate pyrochlores.