Superconducting and mechanical properties of YBCO-Ag composite superconductors

Abstract

The measurements of electrical properties and X-ray structural analysis were made for sintered composite materials prepared by mixing the powders of the ceramic superconductor YBa₂Cu₃O_7−x (YBCO) and the powders of the pure metal element M with with M = Ni, Cu and Ag at 50 vol% proportions. The superconducting and mechanical properties were studied further on the YBCO-Ag system in the wide volume fractions 0 to 92%Ag. The onset of the superconductivity is found to occur 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. The 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 well both superconducting and mechanical properties in the present YBCO-Ag composite system.