Improved Current Densities in MgB2 By Liquid-Assisted Sintering

TL;DR

This study demonstrates that liquid-assisted sintering with GaN additions enhances the critical current density in MgB2 superconductors without affecting the transition temperature, approaching the performance of hot isostatically pressed samples.

Contribution

It introduces a liquid phase sintering method with GaN to improve MgB2's current-carrying capacity while maintaining its critical temperature.

Findings

Jc increased by factors of 2 and 10 at 5K and 20K respectively.

Critical temperature Tc remained unchanged with low-level GaN additions.

Values of Jc approached those of hot isostatically pressed samples.

Abstract

Polycrystalline MgB2 samples with GaN additions were prepared by reaction of Mg, B, and GaN powders. The presence of Ga leads to a low melting eutectic phase which allowed liquid phase sintering and produces plate-like grains. For low-level GaN additions (5% at. % or less), the critical transition temperature, Tc, remained unchanged and in 1T magnetic field, the critical current density, Jc was enhanced by a factor of 2 and 10, for temperatures of \~5K and 20K, respectively. The values obtained are approaching those of hot isostatically pressed samples.