Caracterização elétrica e estrutural de cerâmicas supercondutoras BSCCO preparadas com controle granulométrico dos pós precursores

Abstract

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Results are shown of grain control of powder used in the fabrication of high temperature superconductors (HTSC) pellets. The powder was obtained using co-precopilation of oxalates of the elements composing the Bi:Sr:Ca:Cu:O system, with nominal composition (2:2:2:3). After various calcinations the grains of sizes 40-120 µm were separated using sieves of appropriate mesh. The electric and structural characterization of pellets was made using electrical resistivity technique (DC FOUR PROBE), transport current density, scanning electron microscopy (SEM) and, X-ray diffraction (XRD). The chemical composition was studied with energy dispersive X-ray microanalysis (EDX). The pellets made with grains having average diameter about 40 µm show critical temperature To~=110 K, compatible with the phase (2:2:2:3) and current density about 50 A/cm2 at 5K.