Abstract
We have studied in detail the dependence of the electrical resistivity as a function of temperature of Bi~1.65~Pb~0.35~Sr~2~Ca~2~Cu~3~O~10+δ~ ((Bi,Pb)‐2223) and Bi~1.65~Pb~0.35~Sr~2~CaCu~2~O~8+δ~ ((Bi,Pb)‐2212) ceramic samples. Both types of samples were obtained by a solid‐state reaction method and pressed uniaxially at different compacting pressures ranging from 90 to 600 MPa before the last heat treatment. From electrical resistivity measurements as a function of temperature, we were able to separate contributions arising from both the grains' misalignment and microstructural defects, by using a current‐conduction model. The results suggest that in both compounds the texture degree and the connectivity between grains are improved with increasing compacting pressures. It was found that in the (Bi,Pb)‐2223 samples, even in those obtained at low compacting pressures, the grains exhibit a preferential orientation. A similar effect, but less pronounced, was observed in the (Bi,Pb)‐2212 samples. In both cases, the behavior is different to the one reported in YBCO ceramic samples, in which the grains exhibit random orientation. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)