Enhanced transport critical current of iron-based superconducting joints

Abstract

Superconducting joints are one of the crucial components to make Sr1−xKxFe2As2 (Sr-122) superconducting wires or tapes successful for future high-field, high-homogeneity magnetic application. In this paper, the hot-pressing process for an iron-based superconducting joint of Sr-122 tapes was optimized. The microstructures, superconducting properties and element distribution in the connection areas were researched. The transport properties of the iron-based superconducting joints were enhanced by prolonging the holding time at high pressure, which prevents potassium loss in the iron-based superconducting joint. The best transport critical current that was achieved was 57 A at 4.2 K and 10 T; meanwhile, the critical current ratio (CCR = Icjoint/Icnon-joint) of the joint was realized to be 63.3%, which is the highest value of an iron-based superconducting joint reported so far. These results clearly demonstrate that iron-based superconductors are very promising for high-field magnet applications.