Effect of Water or Organic Solvent on Jc of Re-press formed Superconductors in Bi(Pb)System

Abstract

The effects of water, ethyl alcohol or acetone on the Jc(77K) value of superconductors in the Bi(Pb)-Sr-Ca-Cu-O system were investigated. Starting powders for sintering were prepared by calcining the mixture of the composition (a)Bi_1.8Pb_0.4 Sr₂Ca₂Cu_3.2O_y or (b)Bi_1.98Pb_0.22Sr₂Ca₂Cu₃O_y. The 1st sintered compacts of the former composition (a) were heat-treated by 4 steps and press-formed at 196MPa.
The Jc value of the samples soaked for 288h in water was lower by 25A/cm² than that of the sample without soaking (Jc=40A/cm²). Those of the samples soaked in ethanol and acetone were constant. The higher value of Tc and Jc was obtained for the samples made by more steps of repress-forming and sintering. The values of Tc and Jc of 1st sintered samples without heat-treatment decreased more rapidly with soaking time affected by water and the organic solvents.