Effect of Hydrogen on the Electrical Resistirity of Bi-Sr-Ca-Cu Oxide Superconductors at High Temperature

Abstract

The high temperature electrical resistivity and superconducting properies of Bi-Sr-Ca-Cu-O samples heat-treated in H₂ gas were investigated. The results are summarized as follows:
(1)It was recognized that the measurement of Tc for the Bi₂Sr₂CaCu₂O_y(2212) samples heat-treated at above 473K was impossible because of the great reduction by hydrogen treatment.
(2)With increasing H2 gas pressure during heat treatment at 423K, Tc for the 2212 sample increased, whereas that for the 2223 samples decreased. In this case, the increment of H content was recognized on both of these two kinds of samples. On the other hand, the oxygen content decreased slightly with increasing H₂ gas pressure.
(3)Though the increment of H content was observed on the 2212 specimen heat-treated at as low temperature as 373K for longer period than 48h under H₂ gas pressure of 25atm, the reduction phenomena was hardly recognized.