Irradiation behavior of SrTiO₃ at temperatures close to the critical temperature for amorphization

Damage accumulation on both the Sr and Ti sublattices in strontium titanate (SrTi O3) has been investigated under 1.0 MeV Au+ irradiation at 360 and 400 K, close to the critical temperature for amorphization (∼370 K). Under irradiation at 360 K, the relative disorder on both sublattices follows a nonlinear dependence on ion dose. Amorphization starts from the damage peak region (at a depth of 60 nm) and grows toward the surface and into the bulk. At 400 K, the evolution of point defects to extended defects occurs as ion fluence increases. The disorder initially peaks at a depth of 60 nm, saturates at a disorder level of ∼0.75, and then decreases with further irradiation. At an ion fluence of 6.0× 1015 cm-2, an amorphous layer of ∼10 nm thickness is formed at the sample surface. After annealing at 375 K for 1 h, the buried amorphous layer formed during irradiation at 360 K is recrystallized with planar defects and dislocation loops. However, the surface amorphous layer formed at 400 K irradiation remains amorphous, and fewer defects are observed in the irradiated region. Irradiation-enhanced recrystallization due to high flux electron energy deposition is observed.