The effect of precursor powder size on the microstructure and integranular properties of Bi2223 superconductors

We have studied the effect of precursor powder size on the microstructure and intergranular behavior of polycrystalline Bi2223 superconductors using the XRD, SEM, electrical resistivity and AC susceptibility techniques. Polycrystalline Bi2223 superconductors were prepared from the powders with different milling times. The XRD results show that by decreasing the precursor powder size the Bi2223 phase fraction increases. It was found that the grain size and grain connectivity improved by decreasing the precursor powder size. Analysis of the temperature dependence of the AC susceptibility near the transition temperature (Tc) has been done employing Beans critical state model. The observed variation of intergranular critical current densities (Jc) with temperature indicates that the decreasing of precursor powder size in the Bi2223 system cases an increase in the intergranular critical current density.