The improved superconductive properties of MgB2 bulks with minor Cu addition through reducing the MgO impurity

The minor Cu (<3 at%) addition could significantly reduce the amount of MgO impurity in the in situ sintered MgB2 samples and thus improve the critical current density (Jc) at low field and the critical transition temperature (Tc). The formation of local Mg–Cu liquid at about 485 °C could wrap the neighboring Mg particles and thus protect them from the oxidation during the sintering process. Our results provide a possible route to further improve the superconductive properties of pure or doped MgB2 samples through decreasing the amount of MgO impurity with minor Cu addition.