The Influence of Morphological Aspects in the Reaction Pathway and Superconductive Properties of Bi2223-Ca₂CuO₃ Ceramic Composites

Abstract

A variation of the solid-state matrix technique has been developed as a procedure for the preparation of 2223 bismuth superconducting phases [(Bi,Pb)₂Sr₂Ca_1-nCu_nO_4+2n, n=3]. The adequate processing of samples of nominal compositions 2223+x 0021, obtained both by this procedure and by the polymer matrix method, has allowed the modification of the microstructure of the calcium copper excess, with no noticeable change in that of the 2223 grains. The study of the phase evolution in the processing of the samples has shown that the formation rate of the 2223 phase is faster when the particle size of the calcium cuprate is smaller. A dependence of the intergranular superconducting properties on the secondary phase is observed, appearing as a maximum in J_c0/μ_cer at x=0.2 and x=0.5 for samples prepared by solid state matrix and polymer matrix methods, respectively.