High temperature superconductivity in the Ba-Y-Cu oxide system

Zero resistance was achieved at temperatures as high as 92.5 K for Ba/sub 1.8/Y/sub 1.2/Cu3O/sub 9-y/. The resistance curve also showed an apparent deviation from linearity at about 120 K which suggested the possibility of achieving even higher critical temperatures by optimizing the process. The critical current density estimated from the magnetization curve exceeded 103A/cm2 at 77 K and zero field. The density measured directly by a resistive method was about an order of magnitude lower than that estimated by magnetization. The difference was probably due to the porous structure of the sample. Fabrication of wire and tape conductors was attempted by powder metallurgy and surface reaction techniques. The critical current density (resistive method) of 210 A/cm2 at 77 K and zero field was obtained for the wire sample without sheath. It is expected that this value can also be further improved by optimizing various processing parameters