Damage morphology along ion traces in Au-irradiated Bi₂Sr₂CaCu₂O_x

We systematically observed the damage morphology along ion traces by transmission electron microscope in 230 MeV Au-irradiated Bi₂Sr₂CaCu₂O_x single crystals. The results gave us a basic understanding of how high-energy ions interact with the target atoms, lose their energy, and are stopped. Three types of transitive defect morphologies, large-angle-deflected columnar defects, cascade-defect-dotted columnar defects, and ordered cascade defects, were found to be located between two typical defect morphologies, parallel columnar defects and disordered cascade defects, in different penetration depth regions. The mechanisms for the formation of these transitive defect morphologies were suggested. The analysis of ion-energy deposition in each penetration depth region and the results obtained indicated that our suggested mechanisms are reasonable. This study also supplied us with an effective experimental method to directly estimate the columnar defect size distribution versus ion penetration depth and the ion-energy thresholds to produce columnar defects and cascade defects.