Radiation-induced amorphization of Ce-doped Mg₂Y₈(SiO₄)₆O₂ silicate apatite

Ce-doped Mg₂Y₈(SiO₄)₆O₂ silicate apatite (Ce = 0.05 and 0.5) were irradiated with 1 MeV Kr²⁺ ion beam irradiation at different temperatures and their radiation response and the cation composition dependence of the radiation-induced amorphization were studied by in situ TEM. The two Ce-doped Mg₂Y₈(SiO₄)₆O₂ silicate apatites are sensitive to ion beam induced amorphization with a low critical dose (0.096 dpa) at room temperature, and exhibits significantly different radiation tolerance at elevated temperatures. Ce concentration at the apatite A^I site plays a critical role in determining the radiation response of this silicate apatite, in which the Ce³⁺ rich Mg₂Y_7.5Ce_0.5(SiO₄)₆O₂ displays lower amorphization susceptibility than Mg₂Y_7.95Ce_0.05(SiO₄)₆O₂ with a lower Ce³⁺ occupancy at the A^I sites. The critical temperature (T_c) and activation energy (E_a) change from 667.5 ± 33 K and 0.162 eV of Mg₂Y_7.5Ce_0.5(SiO₄)₆O₂ to 963.6 ± 64 K and 0.206 eV of Mg₂Y_7.95Ce_0.05(SiO₄)₆O₂. We demonstrate that the radiation tolerance can be controlled by varying the chemical composition, and enhanced radiation tolerance is achieved by increasing the Ce concentration at the A^I site.