Effect of Sm addition on (Bi,Pb)-2212 superconductor

The effect of Sm addition on the superconducting properties of (Bi,Pb)-2212 system in bulk polycrystalline form was studied. The Sm content was varied from x = 0.0 (pure) to 0.5 on a general stoichiometry of Bi1.7Pb0.4Sr2.0Ca1.1Cu2.1SmxOy. Phase analysis by XRD, microstructural examination by SEM equipped with energy dispersive X-ray spectrometer (EDS), density measurements and superconductivity characterizations were done to evaluate the relative performance of the samples. Critical current density (Jc) and superconductivity transition temperature (Tc) of Sm added samples were found to be higher than that of the pure sample, i.e. without Sm added. A maximum Jc of 719.4 A/cm2 at 64 K was measured for the SM2 sample which is more than seven times higher than that of the pure sample (Jc = 94.1 A/cm2). Also the Tc of the SM3 sample was the highest (94.1 K) compared to all other samples. Microstructural examination showed distinct variations in the grain morphology of the samples containing Sm. A Sr-rich oxide containing Pb(Bi) and Cu with square rectangular grains with rounded edges was observed in the microstructure of Sm 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.