Microstructure and superconductivity of Cu addition MgB₂wires using Mg₂Cu compound as additional source material

Abstract

The advantages of the MgB2 compound are the high Tc value (39 K) and lower material cost than other superconducting metallic compounds. In addition, MgB2 wire has a shorter decay time for induced radioactive properties than Nb-based superconductors. However, the Jc value of MgB2 wire is poor compared with Nb-based superconductors, and further improvement of Jc is required if the compound is to be used in a future nuclear fusion reactor. In order to improve Jc, we investigated Cu addition using the Mg2Cu compound in MgB2/Fe-sheathed wires through the powder-in-tube (PIT) process. Tc values of Cu addition samples were higher than those of non-Cu addition samples and they were improved with increasing Cu addition. We obtained maximum core Jc values over 100 A mm−2 at 4.2 K under 8 T for 1 and 3 at.% Cu addition samples. Moreover, we found that Cu addition was more effective at improving the value of Jc in low and middle magnetic fields than the SiC addition process.