Effect of Dy2O3 doping on phase formation and properties of MgB2 wires made by the modified internal magnesium diffusion process

Abstract

A series of single-core MgB2 wires was produced by the modified internal magnesium diffusion process, starting with a Mg tube filled with carbon predoped boron powder, which resulted in an extractable MgB2 core allowing thorough investigation of superconducting properties. Carbon contained in the boron powder enhances critical current density (Jc), however, it also reduces the reactivity of boron and thus acts as a MgB2 growth inhibitor. In order to compensate this negative effect, Dy2O3 nanopowder was added into boron powder and the composites were subjected to heat-treatment at increased temperature for a longer time. By this approach, the reactivity of carbon predoped boron was substantially improved, yielding wires with an increased amount of MgB2 of high phase purity with enhanced Jc.