Superconducting joint interface for multi-filamentary Bi2223 tapes fabricated by JIM method

Abstract Recently, we proposed a method of joint by incongruent melting (JIM) for making a superconducting connection between two multi-filamentary Bi2223 tapes. At high temperatures, the Bi2223 phase separates into solid Bi2212 and a liquid phase by incongruent melting. In the JIM method, the Bi2223 filaments in a tape are first melted to Bi2212 and liquid. Then, Bi2212 is connected by the liquid to form a superconducting current pathway. In the present experiment, a joint between multi-filamentary Bi2223 tapes was prepared, resulting in a superconducting joint with a critical current of 8 A at 77 K. We then investigated the microstructure of the superconducting joint interface using X-ray diffraction and SEM/EDS, to clarify the superconducting joint formation. In examining samples prepared using the JIM method, Bi2212 and Sr-Ca-Cu-O system compounds were found at the joint interface, which had a high crystalline orientation.