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,SrZrO_3 was selected as barrier material.Moreover,small amount of Bi2212 was mixed with SrZrO_3 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 f_c exceeded 250 Hz even in an AC perpendicular field at 77K.Transport J_c of the barrier tapes with tightly twisted filaments was in the range of 12-15 kA/cm~2 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.