Critical Current Densities and Irreversibility Fields in Pb-Doped and Pb-Free Bi2Sr2Ca2Cu3Oy Superconductors

Abstract

From the hysteresis in DC magnetization loops, we evaluated critical current densities J c and irreversibility fields B irr of Pb-doped and Pb-free Bi-2223 superconductors which were prepared from nominal compositions Bi1.68Pb0.32Sr1.85Ca1.85Cu2.85BxOy (x=0, 0.01) and Bi2Sr1.6Ca2.4Cu3O10 by different heating processes. The intragrain J c and B irr for the Pb-doped samples were larger than those of the Pb-free one, although the superconducting volume fraction and superconducting characteristics of the three samples are almost the same. This result suggests that effective pinning centers are introduced by the partial substitution of Pb for Bi in Bi-2223.