Significantly enhanced critical current densities in MgB2 tapes made by a scaleable nanocarbon addition route

TLDR

The study investigates the mechanism behind enhanced flux pinning in nanocarbon‑doped MgB₂ tapes. MgB₂ tapes were fabricated via an in‑situ powder‑in‑tube process with varying nanocarbon doping, and TEM revealed intra‑granular dislocations and dispersed nanoparticles within the grains. C‑doped tapes exhibited more than a tenfold increase in critical current density above 9 T, reaching 1.85 × 10⁴ A/cm² at 10 T and 2.8 × 10³ A/cm² at 14 T at 4.2 K, with only a slight Tc reduction, demonstrating their promise for high‑field applications.

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.