Effects of Electronic Energy Loss on Damage Evolution in Oxide Perovskites Under Ion Irradiation

Oxide perovskites (ABO₃) exhibit a range of semiconducting, optical and magnetic properties that identify them as key materials for the advanced multifunctional devices, and understanding the response of these materials and devices to extreme irradiation environments is needed. While 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, the effects of inelastic electronic energy loss, S_e, to target electrons (i.e., ionization) are more complicated. At low ion energies, S_n dominates, and radiation damage by elastic collision processes leads to the accumulation of atomic-level defects and often phase transformations, such as amorphization. When S_e is comparable to S_n, ionization-induced annealing can occur along the ion trajectory, reducing the rate of defect accumulation. High-energy ions with S_e values above a threshold can form amorphous nanotracks due to melt-quenching along a single ion trajectory. In the presence of pre-existing defects, amorphous nanotracks are formed at much lower values of S_e, and the track size increases with S_e and the density of pre-existing defects. Below the threshold for defect-induced amorphous track formation, local melting does not occur; however, ionization-induced annealing of defects is observed due to the inelastic thermal spikes and electronic excitations that enhance defect mobility. Experimental and molecular dynamics results on SrTiO₃ and KTaO₃ will be presented to demonstrate these phenomena.