Síntese de cerâmica supercondutora pelo processo de secagem com fluído supercrítico

Abstract

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In this work we prepared ceramic powders by a wet route using a mixture of nitrates and then dried in supercritical condition (CO2), in order to obtain the system Bi2Sr2Ca2Cu3Ox (BSCCO) with characteristic critical temperature of 110 K. The electrical and structural characterization of pellets fabricated using these powder has been done by measuring the electric resistance (four probe technique), critical transport current, scanning electronic microscopy (SEM), energy dispersive X-ray microanalysis (EDX) and x-ray diffractometry (XRD). The results are compared with these obtained for samples prepared by co-precipitation of oxalates. The analysis shows that exists an influence of the preparation method on the structure and the critical temperature. The time required for the material calcinations decreased drastically. Measurements of critical transport current show that the values obtained for both methods are comparable (50 A/cm2 at 4K).