Development of superconducting joints between iron-based superconductor tapes

Abstract

Superconducting joints are essential for future iron-based superconductor applications. In this study, a process for fabricating superconducting joints between Sr1−xKxFe2As2 (Sr-122) tapes was developed for the first time. The Ag sheath was peeled off from one side of each sample. The exposed superconducting parts of the two tapes were joined and wrapped again with Ag foil. The diffusion bonding of the iron-based superconducting joint was achieved by the hot pressing (HP) process in an Ar atmosphere. The superconducting properties, microstructures, and elements distribution of the joint regions were investigated. The pressure was optimized in order to enhance the transport current of the joints. At 4.2 K and 10 T, a transport critical current Ic of 40 A for the joint was obtained, which was approximately 35.3% of the current capacity of the tapes themselves. Furthermore, the joint resistance was below 10−9 Ω. These results demonstrate that HP was useful for fabricating the superconducting joints.