Intergranular dissipation processes induced by nanodefects in (Bi,Pb):2223 HTS superconductor

By using solid state reaction method, a lot of (Bi,Pb):2223 high temperature superconducting materials were obtained. The effects of partial double substitution for Cu by 3d elements on phase purity and the dynamic of intergranular vortices have been investigated by using X-ray diffraction and a.c. magnetic susceptibility measurements function of temperature and a.c. field amplitude. The effect of 3d ions concentration and the nanodefects located at grain boundaries on the vortex pinning was characterised quantitatively by using the temperature dependence of imaginary part of a.c. magnetic susceptibility for a.c. amplitudes up to 1000 A/m. (authors)