Some aspects of thermal conversion of gels to YBCO and BSCCO superconductors. Removal of carbonates from intermediate phases

The thermal transformation of acetate derived gels: YBCO and BSCCO to respective superconductors has been studied using thermogravimetry, XRD and i.r. techniques. Formation of carbonates was observed during the thermal treatment of all the materials examined. Thermal decomposition of the carbonates turned out to be more difficult in the YBCO than in BSCCO compounds. Nevertheless the negative effect of carbonates on the formation of BSCCO phases has been observed. Removal of carbonates from intermediate phases by low-temperature treatment with nitric acid strongly accelerates formation of the 2223 BSCCO superconducting phase.