Microstructural and superconducting properties of C ₆H ₆ added bulk MgB ₂ superconductor

The effect of aromatic hydrocarbon (benzene, C ₆H ₆) addition on lattice parameters, microstructure, critical temperature (T _c), critical current density (J _c) of bulk MgB ₂ has been studied. In this work only 2 mol% C ₆H ₆ addition was found to be very effective in increasing the J _c values, while resulting in slight reduction of the T _c. J _c values of 2 mol% C ₆H ₆ added MgB ₂ bulks reached to 1.83×10 ⁶ A/cm ² at 15 K and 0 T. Microstructural analyses suggest that J _c enhancement is associated with the substitution of carbon with boron and which also results in the smaller MgB ₂ grain size. The change in the lattice parameters or the lattice disorder is claimed as a cause of the slight reduction in the T _c by carbon addition. We note that our results show the advantages of C ₆H ₆ addition include homogeneous mixing of precursor powders, avoidance of expansive nanoadditives, production of highly reactive C, and significant enhancement in J _c of MgB ₂, compared to un-doped samples.