Phase transitions during ion-beam irradiation of the perovskite-structure oxides

Several perovskite-structure oxide compounds, including CaTiO3, SrTiO3, BaTiO3, KNbO3, and KTaO3 were irradiated by 800 keV Kr+ ions in order to investigate and compare their response to heavy-ion irradiation. The critical amorphization temperature Tc above which amorphization could not be induced, was found to increase in the order SrRiO3 → CaTiO3 → BaTiO3 → KNbO3 → KTaO3. No single physical parameter explains the observed sequence, although Tc correlates well with the melting temperatures. The well-known solid state phase transformations in these materials did not have a significant effect on the dose required for amorphization. Domain boundaries were observed in the pristine samples; however, after only a low dose, the boundaries became poorly defined and with increasing dose, eventually disappeared. Dislocation loops were observed to aggregate at the domain boundaries