Effects of 67.5 MeV Electron Irradiation on Y-Ba-Cu-O and Gd-Ba-Cu-O High-Temperature Superconductors

摘要

High-temperatures superconductors (YBa2Cu3O(6+delta) and GdBa2Cu3O(6+delta), both with delta < or = 1) with TC approx. 92K and manufactured at the University of Houston were irradiated with 67.5 MeV electrons at fluences of 10 to the 13th, 10 to the 14th, 10 to the 15th and 5 x 10 to the 15th electrons/ sq. cm. The irradiation effects were studied by analyzing resistance versus temperature curves developed using the four-probe resistance measuring technique. The YBaCuO sample showed irradiation (.3 Mrad) and an isolated failure to achieve total superconductivity above 77K after the 10 to the 14th irradiation (3 Mrad). The same sample re-established its high-Tc (92K) after subsequent irradiations. This was presumed to indicate microscopic damage to superconducting channels. It also displayed granular crumbling in the vicinity of the electrical contacts. This was interpreted as an effect of the differences in thermal expansion rates between the contacts and the superconductor.