Synthesis and critical current density promotion for Nb-doped 2212-BPSCCO HTc-superconducting materials

Although BPSCCO superconducting regime has very low stability under high oxygen pressures as reported in the literature, we managed to synthesize relatively pure 2212-BPSCCO and their Nb-doped samples having general formula Bi1−xNbxPbSr2CaCu2O8, where x = 0.1, 0.2, 0.4 and 0.6 mole, respectively, at moderate oxygen pressure (∼30 bar). The superconducting measurements proved that the best recorded Tc ∼ 69 K was for the undoped 2212-BPSCCO, while the lowest Tc ∼ 58 K was recorded for the maximum doped sample x = 0.6 mole indicating that superconductive transition temperatures Tcs decrease regularly with increasing Nb-dopant concentration from x = 0.1 to 0.6, respectively. The lattice parameter c exhibited a slight length compression as Nb-dopant ratio increases from 0.1 to 0.6 mole, respectively. From SE-microscopic analysis, the average grain size was estimated and found in between 0.44 and 1.6 μm which is considered relatively high to that reported in the literature. The measured Jc’s values were found to be enhanced remarkably as Nb-dopant concentration increases.