Electron microscopy study of superconducting joint between multifilamentary Bi₂Sr₂Ca₂Cu₃O_10+δ tapes based on incongruent melting method

Abstract We characterized the nanostructures of a superconducting joining regions between multifilamentary Bi 2 Sr 2 Ca 2 Cu 3 O 10+δ (Bi2223) tapes fabricated by incongruent melting method using scanning electron microscopy and transmission electron microscopy. Bi 2 Sr 2 CaCu 2 O 8+x (Bi2212) grains are formed at the boundary between the Bi2223 filaments. Because the c-axis of the Bi2212 and Bi2223 grains are well aligned, the Bi2212 grains are considered to transform from the Bi2223 grains during the incongruent melting process. We confirmed that these Bi2212 and Bi2223 grains connected each other without secondary phase and spaces in the joining region. Critical super current should pass through such the joining regions.