Large irreversibility field in nanoscale C-doped MgB2/Fe tape conductors

TL;DR

This study demonstrates that nanoscale carbon doping significantly enhances the irreversibility field and critical current density of MgB2/Fe tapes, making them promising for high-field applications at 20 K.

Contribution

It reveals that nanoscale C doping improves the magnetic properties of MgB2 tapes, especially at high sintering temperatures, with potential for MRI applications.

Findings

Birr reaches 22.9 T at 4.2 K for C-doped MgB2

Birr at 20 K achieves 9 T, comparable to NbTi

Higher sintering temperatures enhance doping effects

Abstract

We investigated the effect of nanoscale-C doping on the critical current density Jc and irreversibility field Birr of Fe-sheathed MgB2 tapes prepared by the in-situ powder-in-tube method. The tapes were heat treated at 600-950C for 1 h. Higher values of Jc and Birr were seen for 5 at.%C-doped MgB2 tapes at higher sintering temperatures, where substantial substitution of boron for carbon occurred. The C-doped samples sintered at 950C showed the highest Birr, for example, at 4.2 K, the Birr reached 22.9 T. In particular, at 20 K, Birr for the C-doped tape achieved 9 T, which is comparable to the upper critical field of the commercial NbTi at 4.2 K. This role of nano-sized C particles can be very beneficial in the fabrication of MgB2 tapes for magnetic resonance imaging applications at 20 K.