Hot pressing to enhance the transport Jc of Sr0.6K0.4Fe2As2 superconducting tapes

TL;DR

This study demonstrates that hot pressing significantly improves the critical current density of Sr0.6K0.4Fe2As2 superconducting tapes, achieving record Jc values suitable for practical high-field applications.

Contribution

The paper introduces a hot pressing fabrication method that enhances texture, microstructure, and pinning, leading to unprecedented Jc performance in iron-pnictide superconducting tapes.

Findings

Achieved a Jc of 1.2x10^5 A/cm^2 at 4.2 K and 10 T.

Jc remains high (~1.0x10^5 A/cm^2) even at 14 T.

Hot pressing improves texture and microstructure, boosting superconducting performance.

Abstract

High-performance Sr0.6K0.4Fe2As2 (Sr-122) tapes have been successfully fabricated using hot pressing (HP) process. The effect of HP temperatures (850-925 C) on the c-axis texture, resistivity, Vickers micro-hardness, microstructure and critical current properties has been systematically studied. Taking advantage of high degree of c-axis texture, well grain connectivity and and large concentration of strong-pinning defects, we are able to obtain an excellent Jc of 1.2x10^5 A/cm^2 at 4.2 K and 10 T for Sr-122 tapes. More importantly, the field dependence of Jc turns out to be very weak, such that in 14 T the Jc remains ~1.0x10^5 A/cm^2. These Jc values are the highest ever reported so far for iron-pnictide wires and tapes, achieving the level desired for practical applications. Our results clearly strengthen the position of iron-pnictide conductors as a competitor to the conventional and MgB2 superconductors for high field applications.