Enhancement of in-field Jc in MgB2 /Fe wire using single- and multiwalled carbon nanotubes

The authors investigated the doping effects of single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (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 α axis: the SWCNT doped wireMWshortCNT doped wireMWlongCNT doped wire wire, while Jc(B) followed the sequence of the SWCNT doped wire>the MWshortCNT doped wire>the MWlongCNT doped wire>undoped wire. A dominating mechanism behind all these findings is the level of C substitution for B in the lattice.