Enhancement of in-field Jc in MgB2/Fe wire using single and multi-walled nanotubes

TL;DR

This study explores how doping MgB2/Fe wires with single-walled and multi-walled carbon nanotubes affects their superconducting properties, revealing that SWCNT doping enhances critical current density and upper critical field due to higher carbon substitution levels.

Contribution

It provides a systematic comparison of SWCNT and MWCNT doping effects on MgB2/Fe wires, highlighting the role of carbon substitution in improving superconducting performance.

Findings

SWCNT doping yields highest Jc(B) and Hc2.

Doping sequence affects Tc and lattice parameters.

C substitution level correlates with superconducting enhancements.

Abstract

We investigated the doping effects of SWCNTs and MWCNTs on the Tc, lattice parameters, Jc(B), microstructure, and Hc2 of MgB2/Fe wire. These effects systematically showed the following sequence for Tc and the a-axis: the SWCNT doped wire < the MWshortCNT doped wire < the MWlongCNT doped wire < un-doped wire, while Jc(B) followed the sequence of the SWCNT doped wire > the MWshortCNT doped wire > the MWlongCNT doped wire > un-doped wire. A dominating mechanism behind all these findings is the level of C substitution for B in the lattice. The best Jc(B) and Hc2 were obtained on SWCNT doped wire because the level of C substitution for B in this wire is higher than all others.