Radiation effects on YBa2Cu3O7-δ high-Tc superconducting oxide thin film

Effects of radiation of 28 MeV electrons, fast neutrons, 0.5-2.5 MeV ions such as H+, He+, O+, Ar+ and Ni2+ on YBa2Cu3O7-δ thin films were investigated. The normal resistivity and c-axis lattice constant increased with fluence. Below a threshold fluence for each irradiation the critical temperature (Tc) was constant, while above this fluence Tc decreased with fluence. On the other hand, the transport critical current density (Jc) increased in the low fluence range with a maximum value of 4-30% in enhancement ratio at an optimum fluence, and decreased in the high fluence range. The decrease in Jc was supposed to come from the degradation of grain boundaries as well as intragrains. The threshold fluence φt decreased with the mass A of incident ions in the relation, φt/cm-2=1017 (A/amu)-2.5. For each case of irradiation the threshold fluence and the optimum fluence gave 10-2 and 10-4-10-5 dpa, respectively, and at the latter fluence cascade damage regions begin to overlap. (author)