| 摘要 |
PURPOSE:To improve critical current density by low temp.-preheating an oxide superconductor and/or its precursor in an atmosphere of lower oxygen concentration than the air or in non-oxygen atmosphere at the specified temp. before baking it. CONSTITUTION:Water solutions of metallic compounds of Y, Cu, etc., are each neutralized with aqueous ammonia to form fine particles of hydroxides of Y, Cu, etc., which are captured to disperse them in a solvent, such as ethanol. A solution in which metal Ba, etc., are dissolved in ethanol, etc., is added to the disperse solution and the resulting solution is heated in an atmosphere of inert gas to form an superconductive precursor of the prescribed constitutive element ratios from which solvent is removed to form raw material powder. The raw material powder is given a preheating treatment in a low oxygen atmosphere or in a non-oxygen atmosphere at a temp. of 350-500 deg.C for 1-1000hr to remove moisture, solvent and impurities by evaporation. Next, after the powder is formed the prescribed shape and sintered in an oxygen atmosphere at a temp. of about 900-950 deg.C, it undergoes annealing treatment at about 500oC to obtain the objective oxide superconductor with high critical current density. |
