Superconducting joint between iron-based superconductor tapes

TL;DR

This paper presents a novel hot-pressing method to create superconducting joints between Sr-122 tapes, achieving high critical current and low resistance, crucial for practical applications of iron-based superconductors.

Contribution

First demonstration of a diffusion bonding process for iron-based superconductor tapes using hot-pressing to produce effective superconducting joints.

Findings

Transport critical current of 57 A at 4.2 K and 10 T

Joint resistance below 10^-9 Ohm

Optimized pressure and pressing time improve joint performance

Abstract

Superconducting joints are essential for iron-based superconductor's applications in future. In this study, a process for fabricating superconducting joints between Sr1-xKxFe2As2 (Sr-122) tapes is 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 hot-pressing process in Argon atmosphere. The superconducting properties, microstructures and the elements distribution of the joint regions had been investigated. The pressure and pressing times were optimized in order to enhance the transport current of the joints. At 4.2 K and 10 T, a transport critical current Ic of 57 A for the joint was obtained, which is approximately 63.3% of the current capacity of the tapes themselves. Furthermore, the joint resistances dV/dI were estimated from the V-I curve of the joints and the calculated joint resistances values are below 10^-9 Ohm. These results demonstrate that the hot pressing was useful for fabricating the superconducting joint samples.