Coupled Effects of Electronic and Nuclear Energy Loss on Radiation Response of Oxide Perovskites

Oxide perovskites (ABO₃) exhibit fascinating properties that identify them as key materials for the next generation of multifunctional devices, and their response to electron and ion beam irradiation can provide insights into the behavior expected in hybrid perovskites. It is well-established that atomic-level defects are created by elastic energy transfer (nuclear energy loss), S_n, from charged particles to atomic nuclei; however, the effects of inelastic electronic energy loss, S_e, to target electrons are more complicated. At low to medium energies, the response of many oxide perovskites to charged particles is dependent on the ratio of S_e/S_n. At low values of S_e/S_n, radiation damage by elastic collision processes dominates, often leading to phase transformations, such as amorphization. When S_e is comparable to S_n, the coupling of electronic and nuclear processes along the ion trajectory can lead to ionization-induced dynamic recovery, reducing the rate of damage production and accumulation. For high-energy ions with high values of S_e/S_n (>100), the dissipation of electronic energy loss via electron-phonon coupling dominates, and amorphous nanotracks due to melt-quenching along the ion trajectory can form for S_e values above a threshold. In the presence of pre-existing defects, amorphous tracks are formed at much lower values of S_e, and track sizes increase with defect concentration and values of S_e. For charged particles with high S_e/S_n values (>100), but with S_e values below the threshold for amorphous track formation, ionization-induced annealing of defects is observed. Experimental data on SrTiO₃, KTaO₃ and LiTaO₃ will be presented to demonstrate these phenomena. Molecular dynamics simulations combined with the inelastic thermal spike model in these materials confirm the formation of the amorphous tracks due to melt-quenching along the ion trajectory at high values of S_e, while at intermediate values of S_e, defect recovery is demonstrated. Two distinct regimes of ionization-induced recovery are observed in SrTiO₃, and only a single recovery regime is observed in KTaO₃.