Abstract:
Phase evolution and superconducting properties of Nd added (Bi, Pb)-2223 superconductors in bulk form were studied. The amount of Nd was varied from 0.005 to 0.030 on a general stoichiometry of Bi:Pb:Sr:Ca:Cu = 1.85: 0.35:2.0:2.1:3.1. Transport current measurements at 77 K, phase analysis by XRD, microstructural examination by SEM, etc. were carried out to evaluate the relative performance of the samples. Critical current density of all the samples was higher than that of the pure sample (i.e., without Nd added) and it is more than twice for the sample with Nd = 0.020. Transport current in an applied magnetic field of Nd added samples up to a stoichiometry of Nd = 0.020 is much better compared to the pure sample. XRD analysis showed the presence of Bi-2212 even after the last stage of sintering for the samples with Nd = 0.020 and 0.030. Microstructural analysis revealed that the morphology and texturing of all the samples are more or less identical with a slight improvement for the Nd added samples. It is likely that Nd may be getting substituted at Ca or Sr sites creating point defects, which act as flux pinning centres.
