The effect of Sb doping on critical temperature and critical current density of Bi1.6PbxSbySr2Ca2Cu3Oz superconductor

Full text: In an attempt to increase the superconducting volume fraction of the Bi-2223 phase, in this paper, we report the synthesis of Bi1.6PbxSbySr2Ca2Cu3Oz (BPSSCCO) superconductor by the solid state reaction method. The powders of Bi2O3, PbO, CuO, CaCO3, SrCO3 and Sb2O3 are used as starting materials. The samples of Bi1.6PbxSbySr2Ca2Cu3Oz compound, where (x, y) = (0.4, 0.0), (0.35, 0.05), (0.3, 0.1), (0.25, 0.15), (0.2, 0.2), (0.15, 0.25), (0.1, 0.3) , (0.05, 0.35) and (0.4, 0.0), were made. The superconductivity properties of Pb and Sb doped Bi-base superconductor such as critical current density, critical temperature and microstructure have been investigated. The structural analysis was carried out by XRD and SEM measurements. The XRD results show that the unwanted phases in the samples were reduced by increasing the amount of Sb and annealing time. The maximum fraction of Bi-2223 phase obtained in the sample with y= 0.05 and annealing time of 270 hours. The critical current density measurements were performed via V-J curves in liquid nitrogen. The maximum critical current density was obtained in a sample with y=0.2 for annealing time of 270 hours. In order to study the effect of Sb and Pb on the room temperature resistivity, the V-I curves of samples were measured at room temperature. The resistivity of Sb doped samples at room temperature increases when the amount of Sb is increased; it is also decreases by increasing the annealing time. (authors)