Abstract:
The effect of Pr addition on the superconducting properties of the (Bi, Pb)-2212 system in the bulk polycrystalline form was studied. The Pr content was varied from x = 0.0 (pure) to 0.5 on a general stoichiometry of Bi1.7Pb0.4Sr2.0Ca1.1Cu2.1PrxOy. Phase analysis by XRD, microstructural examination by an SEM equipped with an energy dispersive x-ray spectrometer (EDS), density measurements and superconductivity characterizations were done to evaluate the relative performance of the samples. The critical current density (J(C)) and superconductivity transition temperature (T-C) of Pr-added samples were found to be higher than that of the pure sample, i.e. without Pr added. A maximum J(C) of 678.8 A cm (-2) at 64 K was measured for the sample with Pr = 0.2, which is more than seven times higher than that of the pure sample (J(C) = 87.5 A cm (-2)). Also the T-C of the sample with Pr = 0.2 was the highest (88.0 K) compared to all other samples. Microstructural examination showed distinct variations in the grain morphology of the samples containing Pr, and the porosity increases as the Pr content increases. Consequently, there is a significant reduction in the density of the samples as the Pr content increases. A Sr-rich oxide containing Pb (Bi) and Cu with square rectangular grains with rounded edges was observed in the microstructure of Pr-added samples whose composition has been analysed through EDS. But such a secondary phase could not be distinguished from XRD analysis, probably due to the peak overlapping with (Bi, Pb)-2212.
