The effect of the partial substitution of x = 0.02 Fe for Cu in the stabilized (Bi, Pb):2223 phase has been investigated by magnetoresistivity measurements up to 0.7 T. The intra- and intergranular transitions as a function of magnetic field were analysed using versus T curves. The Arrhenius plots are represented by a family of straight lines. The activation energy is proportional to . The main dissipation process is related to the vortex cutting mechanism.

The effect of the partial substitution of Cu by Ni in the stabilized 108 K phase was investigated by electrical resistance and a.c. susceptibility measurements. Up to a Ni concentration x = 0.02 the bending of the R (T) curve above T c can be described in the terms of the Lawrence-Doniach theory. The intergrain and intragrain critical transition temperatures decrease to ∆T CG = 9 K and ∆T j = 10.9 K respectively by the Ni substitution in the Cu-O pyramids.

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The temperature and amplitude of AC field dependencies of both inter-and intragranular T p and T g temperatures of the imaginary peaks of χ′′ has been studied for a sintered single phase (Bi,Pb):2223 superconductor. The AC field dependencies for T p and T g and the relation between inter- and intragrain force densities were discussed by using Müller critical-state model. From the χ′′(T) curve, the values of intergrain magnetic critical current density J cJ was obtained via the application of Bean's critical state model. J cJ (T) dependence near T c agree with the assumption of SNS intergrain junctions.

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