AC LOSSES IN (BI,PB)2SR2CA2CU3OX TAPES

A double peak structure is observed in the AC losses of (Bi,Pb)2Sr2Ca2 Cu3Ox silver-sheathed tapes using a torsion-pendulum oscillator. The l ow-temperature peak is associated to the intragrain flux expulsion, wh ile the high-temperature peak results from a macroscopic current path around the whole sample due to a well-coupled fraction of the grains. The flux pinning by the dislocations forming small-angle grain boundar ies is suggested to control the transport current.