PREPARATION, STRUCTURE AND PROPERTIES OF THE HIGH-TC BI-BASED AND Y-BASED CUPRATES

The structure and some properties of the new bismuth-based high Tc superconductor are discussed and compared to those of the 40K and 90K materials. While the superconducting behavior of the 90K is very sensitive to the oxygen composition and therefore to the annealing procedure, the Bi-based phase is dramatically less affected. But it is more sensitive to the solid state reaction temperature and starting composition. Thus a better control of the chemistry using a solution technique should enhance the performances of this material. The Y-based 90K superconducting oxide has been synthesized using a novel solution technique (Sol-Gel process). Physical properties, including resistivity and critical current, are compared to those obtained by solid state reaction in which the starting materials include carbonates, acetates and nitrates.