The Effect Of Precursor Powder Size On The Microstructureand Intergranular Properties Of (bi,pb)_2sr_2ca_2cu_3o_y Superconductors

摘要

We have studied the effect of precursor powder size on the microstructure and intergranular behavior of polycrystalline (Bi,Pb)_2Sr_2Ca_2Cu_3O_y(Bi-2223) superconductors, using the X-ray powder diffraction (XRD), scanning electron microscope (SEM), electrical resistivity, and AC susceptibility techniques. Polycrystalline Bi-2223 superconductors were prepared from the powders with different milling times. The XRD results show that by decreasing precursor powder size, the Bi-2223 phase fraction increases in sintered samples. It was found that the grain size and grain connectivity improved by decreasing precursor powder size. The analysis of temperature dependence of AC susceptibility near the transition temperature (T_c) indicates that, by decreasing the precursor powder size in the Bi-2223 system, the intergranular critical current density increases. We have estimated the effective volume fraction of the grains in the framework of the Critical State Model based on our experimental results. This estimation shows, the effective volume of the grains increases by decreasing precursor powder size.