Improved critical current densities in MgB2 tapes with ZrB2 doping

TL;DR

This study demonstrates that doping MgB2 tapes with ZrB2 significantly enhances their in-field critical current density, especially at 10 at.% doping, due to nanoscale defects acting as flux pinning centers.

Contribution

The paper introduces a novel doping approach with ZrB2 to improve MgB2 tape performance, highlighting the optimal doping level and underlying flux pinning mechanism.

Findings

10 at.% ZrB2 doping increases Jc by over ten times above 9 T at 4.2 K.

Critical temperature decreases slightly with doping.

Nanoscale defects from ZrB2 act as flux pinning centers.

Abstract

MgB2/Fe tapes with 2.5-15 at.% ZrB2 additions were prepared through the in situ powder-in-tube method. Compared to the pure tape, a significant improvement in the in-field critical current density Jc was observed, most notably for 10 at.% doping, while the critical temperature decreased slightly. At 4.2 K, the transport Jc for the 10 at.% doped sample increased by more than an order of magnitude than the undoped one in magnetic fields above 9 T. Nanoscale segregates or defects caused by the ZrB2 additions which act as effective flux pinning centers are proposed to be the main reason for the improved Jc field performance.