Preparation factor to enhance J(c) (15,000A/cm(2)) of Bi-2223 sintered bulk

Coprecipitate precursor was adopted in this experiment to facilitate synthe sis in the calcination reaction. Coprecipitate powder was calcined on a sil ver base plate instead of an alumina plate. Al impurity content in the calc ined powder decreased below 10 ppm, and 770 ppm of Ag was contained in the calcined powder. The calcined powder was pressed and then sintered at 850 d egreesC in the air with intermediate pressing by cold isostatic press (CIP) method. The critical current density (J(c)) of the sintered bulk increased to be 15,000 A/cm(2) with the three times of CIP and succeeding sintering, Adding Ag2O to the coprecipitate deteriorated superconductivity of the sin tered bulk It is suggested that in the powder calcined on the Ag base plate Ag molecules evaporate from the plate, diffuse into the grain boundary, an d finally improve the weak links during heat-treatment.