Change of Superconducting Parameters of Y-Ba-Cu-O Slabs and Rings due to High-Energy Ion Beams

Abstract

Different high-Tc superconducting Y-Ba-Cu-O samples of slabs and rings have been investigated. Using differently prepared Y1Ba2Cu3O7-d materials, significant deviations between irradiated and unirradiated specimens have been detected in their properties. These investigations demonstrate that unlikely prepared superconductors are differently sensitive to the external irradiation, although they have the same composition. The irradiation applied during these experiments consisted of high-energy Bi-ions with the flux of 5x1010 ions/cm2 and with the energy of 720 MeV. As is experienced, a considerable variation of the magnetic moment in the extent of 19-44% and a significant increase of the critical current density up to 41% can be detected. These originate from the change of the properties of materials due to the irradiation. For the evaluation of the experiments a new fitting method is elaborated for the temperature dependence of the critical current density, providing fully correct results for the whole temperature interval. The A.C. magnetic measurements show, that the irradiation causes to reach the state of the perfect diamagnetism at higher temperatures, than in the case of unirradiated samples. Similarly, the irradiated specimens have much lower losses, than the unirradiated ones and even these smaller values disappear at low temperatures.