Magnetic field processing to enhance critical current densities of MgB2 superconductors

TL;DR

Applying magnetic fields during sintering significantly improves the superconducting properties of MgB2 wires, especially in critical current density and magnetic irreversibility, with notable enhancements in both pure and CNT-doped samples.

Contribution

This study introduces magnetic field processing during sintering as a scalable method to enhance MgB2 superconductor performance, achieving substantial improvements in critical current densities.

Findings

Jc increased by 3-4 times in pure MgB2

Jc increased by up to an order of magnitude in CNT-doped MgB2

Hirr reached 7.7 T at 20 K in CNT-doped samples

Abstract

Magnetic field of up to 12 T was applied during the sintering process of pure MgB2 and carbon nanotube (CNT) doped MgB2 wires. We have demonstrated that magnetic field processing results in grain refinement, homogeneity and significant enhancement in Jc(H) and Hirr. The Jc of pure MgB2 wire increased by up to a factor of 3 to 4 and CNT doped MgB2 by up to an order of magnitude in high field region respectively, compared to that of the non-field processed samples. Hirr for CNT doped sample reached 7.7 T at 20 K. Magnetic field processing reduces the resistivity in CNT doped MgB2, straightens the entangled CNT and improves the adherence between CNTs and MgB2 matrix. No crystalline alignment of MgB2 was observed. This method can be easily scalable for a continuous production and represents a new milestone in the development of MgB2 superconductors and related systems.