Aniline doping and high energy milling to greatly enhance electromagnetic properties of magnesium diboride superconductors

MgB2 bulks were fabricated using milled precursor powders with aniline dopant and the low purity B was used as a starting material. The flux pinning, Bc2 and magnetic Jc of MgB2 are greatly enhanced by aniline doping. The magnetic Jc value of MgB2 sample with 3 wt% aniline is 9.5 × 103 A cm−2 at 5 K and 6 T, 13 times larger than that of the pure one. Furthermore, the liquid aniline can avoid the agglomeration of precursor powder during high energy milling. Long time ball milling can further improve the electromagnetic properties of aniline doped MgB2 samples. At 5 K and 6 T, the Jc of the 80 h 3 wt% sample is up to 5.5 × 104 A cm−2, 6 times larger than that of the 0.5 h 3 wt% one and 77 times larger than that of the 0.5 h pure one (the “80 h” and “0.5 h” refer to ball milling times). These results indicate that the liquid C-containing dopant combined with high energy milling may be an effective way to achieve the excellent electromagnetic properties of MgB2.