Temperature dependence of the in-plane and grains resistivities in Bi-2223 polycrystalline superconductors

Based on transport measurements performed on Bi-2223 polycrystalline superconductors, we have determined the in-plane resistivity, ${\rho }_{ab}\left(T\right)$, the effective grain resistivity, ${\rho }_g\left(T\right)$, and the effective intergranular resistivity, ${\rho }_j\left(T\right)$, by applying a model recently reported by our group. The obtained dependencies allowed us to determine the critical temperatures of ab planes, grains as a whole, and intergranular junctions for four different polycrystalline samples. In addition, we were able to propose a very simple and general method to determine the first two critical temperatures previously mentioned by using measurements performed in polycrystalline superconducting samples comprised by highly anisotropic crystallites. Finally, our results may explain the two-step superconducting transition, observed in the samples set, as a feature of this compound linked to its high electrical anisotropy.