Improved Bi-2223 Flux Pinning Through Chemical Doping

40771 November 13, 1996 American Superconductor Corporation Current state-of-the-art Bi-2223 powder-in-tube HTS composite conductors have achieved performance levels which are rapidly approaching the requirements for many low field applications. However, the utilization of these Bi-2223 composite conductors in applications such as motors and generators (i.e., $3 to $5 billion market) requires significant improvement in their current carrying capabilities in high magnetic field environments at temperatures near 77K. Recent results have demonstrated that this current carrying capability can be increased 100 fold by the introduction of pinning defects into the Bi-2223 grains through proton irradiation. This project will develop a novel, inexpensive chemical approach for introducing pinning defects directly into the Bi-2223 powder. The advantages of this technique include: (1) the ability to selectively control the number and size of the pinning centers, and (2) the formation of a uniform distribution of pinning centers throughout the entire length of a coil or wire. Phase I includes: (1) fabrication and detailed characterization of the chemically engineered pinning defects, and (2) demonstration of the improved field performance of composite Bi-2223 conductors. Anticipated Results/Potential Commercial Applications as described by the awardee: Chemical doping of Bi-2223 powders should allow the fabrication of multifilament composite HTS conductors with improved current carrying capabilities in high-magnetic fields at liquid nitrogen temperature. Specific applications include power transmission cables, motors, generators, SMES, current limiters and transformers.