Radiation effects in high-temperature composite superconductors

We investigate how irradiation with high-energy ions (167-MeV 132 Xe 27+ , 107-MeV 84 Kr 17+ , and 48-MeV 40 Ar 8+ ) and 2.5-MeV protons affects the critical parameters of high-temperature superconductor tapes based on YBa 2 Cu 3 O 7– x and GdBa 2 Cu 3 O 7– x compounds. The ion ranges in the multilayer structures under study and the thermal regimes of the irradiated samples are calculated using SRIM and thermal-peak models. The calculated results make it possible to estimate the size of radiation-induced defects which serve as the pinning centers of Abrikosov vortices. The performed investigations enable us to reveal that, in the irradiated structures, an increase in the critical current, improvement in the adhesion between the superconducting layer and the substrate, and a reduction in internal stresses are observed under exposure to low levels of Ar- and Kr-ion irradiation. The critical current and the critical temperature decrease at higher fluences and, finally, the phenomenon of superconductivity disappears if the fluence continues to increase. In the case of 2.5-MeV proton irradiation, the radiation resistance of the GdBa 2 Cu 3 O 7– x samples is found to be higher than that of the YBa 2 Cu 3 O 7– x tapes.