Effect of the Cooling Rate on Superconductivity of Bi-System Superconductor

The effect of the cooling process on superconductivity has been studied for the samples with nominal compositions of Bi sub(1.6)Pb sub(0.5)Sr sub(2.0)Ca sub(2.0)Cu sub(3.0)O sub(z) sintered at 1123K for 80h in air. The results are summarized as follows: (1) Samples which have the cooling rates of the range from 1 to 100K/m in. have shown good superconductivity, the critical temperature > 100K and the critical current density > 80 A/cm super(2). (2) From TG measurements, the two oxidation peaks in cooling process have been observed, where these high and low temperature peaks seem to be related to the reaction of 2223 and 2212 phases, respectively. (3) The critical current density has increased from 80 to 165A/cm super(2) by the cooling process with holding at 1093K for a few hours.