Enhancement of the critical current density of internal Mg diffusion processed MgB2 wires by the addition of both SiC and liquid aromatic hydrocarbon

Abstract

We applied the addition of both SiC and liquid aromatic hydrocarbon to the internal Mg diffusion (IMD) processed MgB2 wires. The liquid aromatic hydrocarbons used in this work are toluene, p-ethyltoluene and p-dimethylbenzene. The engineering critical current density (Je) and the critical current density (Jc) calculated for the cross-sectional areas of the reacted layer are compared to those of the IMD processed wires without aromatic hydrocarbon addition. All wires with co-addition of aromatic hydrocarbon and SiC show much smaller field dependence of Je (Jc)–B curve similarly to the wires with only SiC addition and, hence, larger Je (Jc) in high magnetic fields compared to the wires processed from pure B. Furthermore, the SiC+toluene co-added wires show larger Je and Jc values in entire magnetic fields which is independent of the heat treatment temperature while that of the other co-added wires is depending on the heat treatment temperature. The highest Je and Jc at 4.2K and 10T obtained in this work are 3700A/cm2 and 48,000A/cm2, which were achieved for the SiC+dimethylbenzene co-added wires heat treated at 670°C and the SiC+toluene co-added wires heat treated at 640°C. Those results indicate that the co-addition of SiC and liquid aromatic hydrocarbon is one of the promising methods to improve the Jc as well as Je of the IMD processed MgB2 wires.