Structural Damage and Recrystallization Response of Garnet Crystals to Intense Electronic Excitation

The susceptibility to irradiation-induced damage, the fundamental mechanism of the relaxation kinetics, and the corresponding recrystallization effect related to the cation radius ratio are comprehensively investigated for Y₃Al₅O₁₂ and Gd₃Ga₅O₁₂ garnet crystals under 645 MeV Xe³⁵⁺ irradiation with different fluences of 5 × 10¹¹–3 × 10¹² ions cm⁻². Regarding different lattice distortion and swelling levels, the observed microstructure transformations to disordered and amorphous phases, and corresponding hillock dimensions, consistently confirm that Gd₃Ga₅O₁₂ has a higher susceptibility to radiation damage than Y₃Al₅O₁₂. Combined with iTS model calculations, although Y₃Al₅O₁₂ has higher atomic temperature and energy deposition than Gd₃Ga₅O₁₂ under the same ion velocity and electronic energy loss, the relatively high thermal conductivity and specific heat coefficient of Y₃Al₅O₁₂ crystals enhance the conduction and dissipation of deposition energy, and Gd₃Ga₅O₁₂, with a higher cation-radius-ratio (r_A/r_B), is more easily damaged to amorphous phase due to the less favorable kinetics of ordering and recovery of a melted track region to the crystalline phase. Additionally, the significant bandgap modification in spectral ranges of 5.88–6.75 eV for Y₃Al₅O₁₂ and 4.83–5.41 eV for Gd₃Ga₅O₁₂, and the enhancement of defect-assisted-related luminescence are achieved, providing a basis to design novel optoelectronic devices in microelectronics fields.