Effect of nano-size ZrO2 addition on the flux pinning properties of (Bi, Pb)-2223 superconductor

We investigated the microstructure and flux pinning capability of the bulk (Bi, Pb)(2)Sr2Ca2Cu3Oy system (denoted as (Bi, Pb)-2223) with 0.0-0.3 wt% nano-size ZrO2 particles (10-20 nm) addition synthesized by solid state reaction. Phase analysis by x-ray diffraction (XRD), granular structure examination by scanning electron microscopy (SEM), microstructure investigation by transmission electron microscopy (TEM) equipped with energy dispersive x-ray spectrometer (EDS), critical current density dependence on the applied magnetic field J(c)(H) and electrical resistivity rho(T, H) were carried out. The results show that activation energies of vortex flux motion U(H), critical current density Jc(H) behavior in applied magnetic field and volume pinning force density F-p are enhanced by the addition of 0.1 wt% ZrO2. The pinning force analysis and microstructure observations indicated that the improvement of flux pinning is suggested to originate from the introduction of extrinsic pinning centers due to the formation of normal nano-sized Zr-rich phase.