Optimization of critical current density of bulk YBCO superconductor prepared by coprecipitation in oxalic acid
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YBa2Cu3O7−x(YBCO) superconductor powder was prepared from mixtures of solutions containing yttrium, barium, and copper nitrates by coprecipitation in oxalic acid. Single-phase YBCO was obtained from a solution mixture of 14 vol% excess of barium nitrate and 12 vol% excess of copper nitrate relative to the stoichiometry of YBCO. The optimal pH in the coprecipitation process was determined to be 6.6–6.7 which was obtained by using 12 vol % excess oxalic acid anhydrous solution of the required oxalic acid to convert all metal cations to oxalates and adding a dilute ammonium hydroxide solution. The measurement of critical current density, Jc, of bulk YBCO prepared by the coprecipitation, showed a trend that the Jc increased together with the degree of orthorhombic distortion of YBCO phase which depended on the sample density and the content of impurity phases.
KeywordsBarium Oxalate Yttrium Oxalic Acid Ammonium Hydroxide
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