Significantly enhanced critical current densities in MgB2 tapes made by a scaleable, nano-carbon addition route

TL;DR

This study demonstrates that nano-carbon doping significantly enhances the critical current density of MgB2 tapes in high magnetic fields, making them more suitable for high-field applications.

Contribution

The paper introduces a scalable nano-carbon addition method to improve flux pinning and critical current densities in MgB2 tapes.

Findings

Jc increased by over an order of magnitude above 9 T

At 4.2 K, Jc reached 1.85x10^4 A/cm^2 at 10 T

Critical temperature decreased slightly with doping

Abstract

Nanocarbon-doped Fe-sheathed MgB2 tapes with different doping levels were prepared by the in situ powder-in-tube method. Compared to the undoped tapes, Jc for all the C-doped samples was enhanced by more than an order of magnitude in magnetic fields above 9 T. At 4.2 K, the transport Jc for the 5 at% doped tapes reached 1.85x104 A/cm2 at 10 T and 2.8x103 A/cm2 at 14 T, respectively. Moreover, the critical temperature for the doped tapes decreased slightly. Transmission electron microscopy showed a number of intra-granular dislocations and the dispersed nanoparticles embedded within MgB2 grains induced by the C doping. The mechanism for the enhancement of flux pinning is also discussed. These results indicate that powder-in-tube-processed MgB2 tape is very promising for high-field applications.