J_c enhancement by partial melting in BSCCO 2223 ceramics

Summary

The application of partial melting techniques to the densification of BSCCO 2223 ceramics is presented. A new method has been developed, that avoids the peritectic decomposition of the 2223 phase and exploits the existence of a limited region of the phase diagram, occurring for composition richer in Ca and Cu, in which this phase is the only BSCCO phase coexisting with the liquid. This allows the densification process assisted by the liquid phase, limiting at the same time the formation of undesired intergrowths of lower T_c phases. In comparison with the usually adopted processes, the new method results in a dramatic decrease of the post-treatment times, which are typically limited to a few hours. By optimising the thermal as well as the temporal parameters governing a standard two-steps procedure, values of J_c of the order of 10³ A cm^-2, at 77 K, can be obtained for a global process time not exceeding 6 hours.