Irradiation-induced redox behavior in Ce-doped Lu2Ti2O7 pyrochlores

Long-term self-irradiation of high-level waste (HLW) matrices may cause diverse microstructural changes, which can degrade their immobilization performance. This study reports the irradiation-induced redox response of Ce-doped pyrochlores, which can be attributed to the damage process in pyrochlores. Lu2Ti2O7 and Lu1.46Ce0.54Ti2O7+x pyrochlores were irradiated by 400 keV Ne2+. The coordinate environment of the elements was characterized by X-ray photoelectron spectroscopy, X-ray diffraction (XRD), and Raman spectroscopy, while the chemical compositions of the samples were analyzed by scanning electron microscopy. First, the irradiation-induced oxidation of Ce was observed in Lu1.46Ce0.54Ti2O7+x at doses of 0–0.052 dpa, and the Ce3+ content was found to decrease from 61.73% to 58.44%. When the dose was increased to 0.261 dpa, the valency of Ce was reduced, and the Ce3+ content increased to 59.25%. Herein, the reduction behavior is discussed in terms of amorphization and recrystallization in the irradiated Lu1.46Ce0.54Ti2O7+x. This irradiation-induced redox behavior of Ce-doped pyrochlores provides another perspective for predicting the long-term performance of HLW matrices in repositories.