Low-temperature synthesis of SmFeAsO0.7F0.3 wires with high transport critical current density

TL;DR

This paper reports a novel low-temperature synthesis method for SmFeAsO0.7F0.3 superconducting wires, achieving high critical current density and offering a safer, more convenient fabrication process for iron-based superconductors.

Contribution

The study introduces a low-temperature (850-900°C) synthesis process for SmFeAsO0.7F0.3 wires, resulting in high transport critical current density and improved fabrication safety.

Findings

Achieved a critical current density of ~1300 A/cm^2 at 4.2 K.

Synthesis at lower temperatures is feasible and effective.

Weak-linked grain boundaries affect current transport.

Abstract

Ag-sheathed SmFeAsO0.7F0.3 (Sm-1111) superconducting wires were prepared by a one-step solid state reaction at temperatures as low as 850~900C, instead of commonly used temperatures of 1150~1250C. The X-ray diffraction pattern of the as-sintered samples is well indexed on the basis of tetragonal ZrCuSiAs-type structure. We characterized transport critical current density Jc of the SmFeAsO0.7F0.3 wires in increasing and subsequently decreasing fields, by a resistive four-probe method. A transport Jc as high as ~1300 A/cm^2 at 4.2 K and self field has been observed for the first time in Sm-1111 type polycrystalline superconductors. The Jc also shows a rapid depression in small applied fields as well as a magnetic-history dependence, indicating weak-linked grain boundaries. The low-temperature synthesis method can be very beneficial to fabricating the RE-1111 iron oxynictides in a convenient and safe way.