SUPERCONDUCTING AND MECHANICAL-PROPERTIES OF YBCO-AG COMPOSITE SUPERCONDUCTORS

Measurements of electrical properties and X-ray structural analysis were made for sintered composite materials prepared by mixing the powders of the ceramic superconductor YBa2Cu3O7-x YBCO) and the powders of the pure metal element M with M = Ni, Cu and Ag at 50 vol% proportions. The superconducting and mechanical properties were studied in the volume fractions 0 to 92% Ag. The onset of superconductivity occurs even for samples containing more than 80 vol% Ag. The value of the critical current density is increased initially by adding silver. The mechanical strength against fracture is also improved. X-ray structural analysis coupled with scanning electron micrographs revealed that silver and YBCO remain intact after sintering and that fine YBCO particles form continuous networks around homogeneously distributed silver particles. This explains the superconducting and mechanical properties in the YBCO-Ag composite system.