PURPOSE:To improve critical electric current density by adding V or Nb to a Bi-Sr-Ca-Cu-O system or a Bi-Pb-Sr-Ca-Cu-O system superconductive substance so as to be a specific weight ratio to Cu. CONSTITUTION:Organic acid salt, etc., of Bi, Sr, Ca and Cu are mixed so as to be a fixed composition and further a compound of V or Nb in an amount making a weight ratio of V/Cu or Nb/Cu to be 0.005-0.07 is added, then dis solved in water, thus burned with heating in air to prepare mixed powder of oxides and calcined in an atmosphere of Ar.O2 mixed gas, then press-molded, thus burned in an atmosphere of Ar.O2 mixed gas to obtain a target material. Next, said target is sputtered on a heated base plate of MgO single crystal by Ar.O2 mixed gas in 1.8-2.3X10-7 Torr initial degree of vacuum to form a film. Thereafter, resultant film is heated in an atmosphere of Ar.O2 mixed gas and subjected to annealing treatment in an O2 atmosphere to afford a thin film of Bi-Sr-Ca-Cu-O system superconductive substance having about 3000-3500 Angstrom film thickness. A thin film of Bi-Pb-Sr-Ca-Cu-O system superconductive sub stance is obtained in the same manner.
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