Development of High Performance Superconducting Materials and Wires for Next Generation

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The goal of the present research are to improve the chemical and Structural stability and critical current densities of high temperature superconductors for next generation and to establish the manufacturing method for short and long length conductors for practical applications at liquid nitrogen temperature. While the mercury(Hg)-based cuprate superconductors have been known to be chemically rather unstable and its preparation process is not simple, we have found that doping of a small amount of transition ions such as rhenium(Re) or chromium(Cr) is quite effective in stabilization of the compounds. Single crystals of Re-doped Hg-Ba-Ca-Cu-O were successfully grown in both bulk and thick film tapes by the melt-solidification method. The Ag/Cr coated Ni foil wag found to be the moat favorite substrate for Hg-based tapes. Mechanisms of the improved flux pinning properties of heavily Pb-doped and oxygen controlled Bi2212 single crystal were elucidated. Processing techniques of Bi(Pb)2212./Ag composite tapes has been also developed.