High-performance Ba1-xKxFe2As2 superconducting joints for persistent current operation

TL;DR

This paper demonstrates a simple cold-pressing method to create high-quality superconducting joints in Ba-122 wires, achieving high critical current ratios and extremely low joint resistance, advancing practical high-field superconducting applications.

Contribution

It introduces a novel cold-pressing fabrication technique for Ba-122 superconducting joints with unprecedented CCR and low resistance, enabling practical high-field superconducting devices.

Findings

Achieved a critical current of 105 A at 4.2 K and 10 T.

Obtained a joint resistance of 2.7x10^-13 ohm at 4.2 K.

Realized a critical current ratio of 94.6% in the joint.

Abstract

Superconducting joints are one of the key technologies to make Ba1-xKxFe2As2 (Ba-122) superconducting wires or tapes for high-field applications. Herein, superconducting joints were fabricated by a simple cold-pressing method, and the joint resistance of the iron-based superconducting joint was estimated for the first time. The superconducting properties, microstructures, and elements distribution in the joint regions were investigated. At 4.2 K and 10 T, a transport critical current Ic of 105 A for the joint was obtained, and the critical current ratio (CCR= Ic-joint/Ic-tape) of the joint was 94.6%. On the other hand, the joint show very low joint resistance of 2.7x10^-13 ohm in self-field at 4.2 K. Among iron-based superconductors (IBS), this work is the first to successfully realize a superconducting joint with such high CCR and low joint resistance. This work shows great potential to apply Ba-122 in a range of practical applications, where superconducting joints are essential.