| Crystalline oxides with structures related to fluorite (CaF2) have become potential candidate ceramics that can be used in nuclear waste immobilization, fission reactor and future fusion reactor. One of the important fluorite derivatives is the crystal with formula A2Ti2O7The ability of their irradiation resistance has been studied for a long time, and they have exhibited different radiation-induced microstructure transformations under various irradiation conditions.This project studies the preparation method and ion irradiation effects of these fluorite derivatives of A2Ti2O7, and mainly explains the mechanism of radiation-induced amorphization, to better understand their ability of irradiation resistance. We synthesized many ceramic pellets of Gd2Ti2O7and Lu2Ti2O7by using conventional ceramic processing. Then these ceramic pellets were irradiated with600keV Kr3+ions to fluences of4×1015ions/cm2and1.45×1016ions/cm2at room temperature and high temperature (450℃), respectively. Irradiation-induced microstructural evolution in the pellets was observed by using grazing incidence X-ray diffraction (GIXRD) at angles from0.1°to3°and cross-sectional transmission electron microscope (TEM). It was found that the irradiated LU2Ti2O7layer undergoes significant radiation-induced amorphization at room temperature, and no amorphization at450℃. In addition, nanocrystals were observed in the irradiated Lu2Ti2O7samples under fluence of4×1015ions/cm2at room temperature.We present here a detailed discussion based on the following three aspects:(1) ion fluences effects. The experimental results showed that the fracts of radiation-induced amorphization increased with the increased ion fluences in Lu2Ti2O7samples;(2) temperature effects. The irradiated samples experienced a significant radiation-induced amorphization transformation at room temperature, whereas no amorphization at450℃;(3) ionic radius ratio effects. The irradiated Gd2Ti2O7samples were more susceptible to amorphization than Lu2Ti2O7. |
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