The superconducting properties of Cu-doped MgB2 bulks prepared by a high-energy milling method

The Cu-doped MgB2 bulks were prepared by a high-energy milling and subsequent sintering method. Compared to the pure and Cu-doped bulks prepared only by sintering, the critical current density (Jc) of the milled Cu-doped samples was improved with a slight decrease in critical transition temperature (Tc). Using the phase analysis and microstructure observation, it has been found that the MgB2 grains in the milled Cu-doped sample was refined with the high-energy milling and thus provided more grain boundary pinning, which was contributed to the improvement of Jc at high field.