c-axis I-V characteristics in highly c-axis-oriented (Bi, Pb)2Sr2Ca2Cu3Ox silver-sheathed tapes

We have measured c-axis I-V characteristics of highly c-axis-oriented (Bi,Pb)(2)Sr2Ca2Cu3Ox silver-sheathed tapes (Bi2223/Ag) in the field H less than or equal to 0.5 T near T-c (80 to 110 K). The Josephson junction effect is observed. In each I-V curve a voltage jump V-0 is clearly found which may correspond to the transition from states with Cooper tunneling to states with quasi-particle tunneling. This implies the Josephson coupling between the grains or between the CuO2 tri-layers in Bi2223/Ag tapes along the c-direction. The temperature dependence of the superconducting gap Delta(T) can be successfully scaled to that obtained from BCS theory. The gap Delta does not depend much on a magnetic field of H less than or equal to 0.5 T for H parallel to c. The voltage jumps observed in the experiments are not as steep as in a single SIS junction, which may originate from the variety of junctions in Bi2223/Ag tapes or the thermal fluctuation.