F. Rizzo
Pontifícia Universidade Católica - PUC-Rio, Rio de Janeiro, Brazil

Development of High-Temperature Superconducting Devices in the
Bi-Sr-Ca-Cu-O System

High-temperature superconductors (HTSC) have shown a great potential for the substitution of conventional materials employed in devices and equipments of the electrical sector, due to their capacity to transport high current densities with low energy losses. In addition, thanks to a number of properties typical for superconductors, new electrical devices can be developed.
Since 1996, through a collaboration between PUC-Rio and CEPEL, research activities have been conducted for production of HTSC devices in the Bi-Sr-Ca-Cu-O system. The first activity addresses the production of Bi-2223/Ag tapes, and has successfully led to a new fabrication method, which reduces significantly the total heat treatment time, besides increasing the processing window and leading to critical current densities (Jc) larger than 30.000 A/cm2 at 77 K. The second activity is directed to the production of Bi-2212 blocks for fault current limiters. Processing of these blocks has been continually improved and transition temperatures of 97 oK, Jc of 1100 A/cm2 under DC current and 3150 A/cm2 under AC have been obtained.
The paper will discuss the experimental techniques relevant to the research and will provide examples of the Materials Science theoretical background involved in the research.

Acknowledgments
The author appreciates the contribution of his co-authors B. Marinkovic (PUC-Rio), S. K. Xia, M. B. Lisboa, A. Polasek, L. A. Saléh, E. T. Serra (CEPEL - Electric Power Research Center, Rio de Janeiro, RJ, Brazil).