Comparative studies of the superconducting properties of Bi2Sr2CaCu2O8+delta and Bi1.7Pb0.3Sr2CaCu2O8-delta/Ag random composites

We report the results of the study of the resistive transition and the scre ening effect on, similar random composites made of a silver matrix containi ng sintered superconducting grains of bismuth phase with two different stoi chiometries. We show that most of the observed behaviors are compatible wit h a phenomenological approach in which the intergrain junctions behave as w eak links whose the state depends strongly on, temperature and field. We fi nd that these links a much weaker in one of the series of samples.