Preparation and characterization of superconducting (YBa₂Cu₃O _x -Ag) composites obtained by sol-gel method

Abstract

For the first time a simple sol-gel method has been developed for the preparation of [YBa₂Cu₃O _x -Ag] composites using nitrates of Y, Ba, Cu, and Ag. For the two composites (with 10 and 20 wt% Ag), the electrical resistivities and magnetic susceptibilities (both alternating and direct current) show critical temperatureT _c (zero) around 90–91 K. The X-ray diffraction studies indicate no major change of lattice parameters for the orthorhombic phase. The critical current density,J _c, is found to be around 200 A cm⁻² at zero field and 80 K. The degradation ofT _c of the composites in presence of water is also very low, similar to the previous observations. This sol-gel method could be used for the large-scale production of superconducting composite powders necessary for drawing wires/tapes or targets for sputtering.