Highly dense and textured superconducting (Bi,Pb)2Sr2Ca2Cu3O10+δ ceramic samples processed by spark-plasma texturing

Consolidated powders of the superconducting cuprate Bi1.65Pb0.35Sr2Ca2Cu3O10+delta (Bi-2223) by the spark-plasma texturing (SPT), spark-plasma sintering (SPS), and the traditional solid-state reaction method were investigated by several techniques and their features compared. The results show that SPT samples exhibit a higher degree of texture, as inferred by a Lotgering factor of similar to 0.73 along the [001] direction and a relative density of 96% of the theoretical value. From magnetic hysteresis loops M vs. H at 5 K, the intragranular critical current densities along two applied magnetic field orientations, J(c0)(c) and J(c0)(ab) relative to the compacting pressure direction, were determined. The anisotropy factor, gamma(J)=J(c0)(ab)/J(c0)(c), yielded an estimate of similar to 2 in the SPS sample and similar to 19 for samples obtained via the SPT method. In the latter samples, J(c0)(c) at 5 K is close to 1.3 x 10(8) A/cm(2), a value higher than others found for the same compound. The temperature dependence of the electrical resistivity, rho(T), analyzed within the framework of a current conduction model for granular superconductors, supports the higher degree of texture of SPT samples and indicates changes in the oxygen content when samples are subjected to a post-annealing heat treatment. All the results reveal the promising capabilities of the SPT method for improving volume density, texture, and grain boundary connectivity of superconducting Bi-2223 materials. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.