Effect of carbon black doping on the microstructure and critical properties of MgB2 superconductor

We selected amorphous, nano-size carbon black (10–30nm) as a dopant for MgB2 superconductor to improve critical current density (Jc) at high magnetic field. We fabricated the MgB2−xCx (x=0, 0.01, 0.05, and 0.1) bulk superconductors using an in situ technique and evaluated the effects of doping on phase formation, microstructure, and critical properties.