Progress in reducing AC magnetization losses of Bi2223/Ag tapes by introducing interfilamentary oxide barriers

This paper presents our recent progress for the development of low-loss Bi2223/Ag tapes with interfilamentary oxide barriers. For the compatibility with Bi2223 superconductors, SrZrO3 was selected as barrier material. Moreover, small amount of Bi2212 was mixed with SrZrO3 to improve its ductility for cold working. By controlling the thickness of barrier layers among the filaments, reducing the tape width (<3 mm) and twisting the filaments tightly (<5 mm in twist pitch lengths), coupling frequency fc exceeded 250 Hz even in an AC perpendicular field at 77 K. Transport Jc of the barrier tapes with tightly twisted filaments was in the range of 12-15 kA/cm2 at 77 K and self-field. At 50 mT and 50 Hz, the twisted barrier tapes showed 60%-70% lower perpendicular field losses than the conventional 4 mm-width tape with fully coupled filaments.