Temperature dependence of the intragrain critical current density in polycrystalline Ag-sheathed Bi(2223) tapes

The temperature dependence of the intrinsic (Bi,Pb)(2)Sr2Ca2Cu3O10 current density has been evaluated inside Ag sheathed tapes. By comparing transport and magnetic measurements performed on multifilamentary (Bi,Pb)(2)Sr2Ca2Cu 3O10 tapes, we individuate a domain of the H-T plane where the current dens ity is limited by the quality of the boundaries between neighboring grains and the tape behaves as a granular superconductor and, on the contrary, the domain where it behaves like a single crystal. At temperatures below 30 K in absence of applied fields, we find that the intragrain current density i s about an order of magnitude larger than the transport current density.