Strong Pinning Enhancement in MgB2 Using Very Small Dy2O3 Additions

TL;DR

This study demonstrates that very small Dy2O3 additions significantly enhance the critical current density of MgB2 superconductors without affecting the transition temperature, through formation of nano-scale precipitates and improved grain connectivity.

Contribution

It introduces a simple in-situ doping method with Dy2O3 that markedly improves MgB2's superconducting performance at low magnetic fields.

Findings

Jc increased by a factor of 4 at 6K, 1T with 0.5 wt.% Dy2O3

Nano-scale DyB4 and MgO precipitates observed within grains

Room temperature resistivity decreased, indicating better grain connectivity

Abstract

0.5 to 5.0 wt.% Dy2O3 was in-situ reacted with Mg + B to form pinned MgB2. While Tc remained largely unchanged, Jc was strongly enhanced. The best sample (only 0.5 wt.% Dy2O3) had a Jc of 6.5 x 10^5 A/cm^2 at 6K, 1T and 3.5 x 10^5 A/cm^2 at 20K, 1T, around a factor of 4 higher compared to the pure sample, and equivalent to hot-pressed or nano-Si added MgB2 at below 1T. Even distributions of nano-scale precipitates of DyB4 and MgO were observed within the grains. The room temperature resistivity decreased with Dy2O3 indicative of improved grain connectivity.