Damage evolution and annealing of Au-irradiated samarium titanate pyrochlore

Damage evolution and thermal recovery of 1 MeV Au²⁺ irradiated samarium titanate pyrochlore (Sm₂Ti₂O₇) single crystals were studied by Rutherford backscattering spectroscopy and nuclear reaction analysis. The damage accumulation follows a nonlinear dependence on dose that is well described by a disorder accumulation model, which indicates a predominant role of defect-stimulated amorphization processes. The critical dose for amorphization at 170 and 300 K is ∼0.14 dpa, and a higher dose of ∼ 0.22 dpa is observed for irradiation at 700 K, which agrees with previous in-situ transmission electron microscopy (TEM) data for polycrystalline Sm ₂Ti₂O₇. Annealing in an ¹⁸O environment reveals a damage recovery stage at ∼ 850 K that coincides with a significant increase in ¹⁸O exchange due to oxygen vacancy mobility. This thermal recovery stage is also consistent with the critical temperature for amorphization measured by in-situ TEM in polycrystalline samples.