Enhancements of critical current density in the BiPbSrCaCuO superconductor by Na substitution

Abstract

In this paper, we investigated the influences of Na substitution on the enhancements of critical current density (Jc) in the BiPbSrCaCuO (BPSCCO) superconductors. The Bi1.6Pb0.4Sr2Ca21xNaxCu3O10+¤ (where x was ranged from 0 to 0.1) polycrystalline samples were fabricated using solid state reaction technique. The zero electrical critical temperature (Tc) of Na-substituted BPSCCO samples was found to be slightly higher than that of Na-free BPSCCO one. Magnetization Jc data measured at 65 K with field applied parallel to the c-axis of the samples showed that Jc of Na-substituted BPSCCO samples were enhanced. Possible reasons for the Jc enhancements were attributed to the effective flux pinning by crystal defects at Ca layers generated by Na substitution. Improvements of volume pinning force (Fp) in terms of magnitude and position of Fpmax were also obtained.