ABSTRACT
A lot of experimental and theoretical studies have accumulated with regard to the radiation effects of high-Tc superconductors. Among these studies, articles on YBCO (Y-Ba-CuO) are the most in the number and those on Bi-based superconductors (BSCCO, Bi-SrCa-Cu-O) are next. In the first stage of the study of radiation effects, many reports deal with the change in the transition temperature (Tc). However, the recent advances in this field have focused on the enhancement of critical current density, partly because of the application of high-rc materials and partly due to the new physics in flux dynamics. As concerns defect structures, electrons, neutrons, and light ions produce point defects and clusters. Point defects have a weak pinning force and are effective only at low temperatures. Clusters can be effective even at higher temperatures due to their strong pinning forces but are complicated regarding their structure such as size and shape. The diversity of the clusters causes ambiguity regarding the experimental results. Many experiments during the early stage dealt principally with those concerning point defects and clusters. After the discovery of columnar defects produced by high-energy heavy-ion bombardments, the study of radiation effects conferred on the pining mechanism of vortices in columnar defects. The columnar defects product strong pinning forces and also are simple as regards their structures.
