Properties of $rm MgB_2$ Superconductor by Doping Impurity of SiC, Graphite, $rm C_60$ , and C Nano-Tube

Since MgB 2 superconductor was discovered by Akimitsu, many scientists has been studied this new intermediate temperature superconductor material. Recently Dou reported the critical current density and flux pinning of MgB 2 is enhanced by doping of SiC nano powder, and Fujii reported MgB 2 superconductor made by the powder-in-tube in-situ process using MgH 2 as a precursor powder enhanced the critical current density especially under high magnetic field. Also Matsumoto reported the irreversibility field of MgB 2 tape prepared by the in-situ powder in tube process using MgH 2 as a precursor powder increased to 23 T by the SiC doping. These results show MgB 2 has high potential as a strong candidate for a practical use. We study the effects of doping nano carbon impurity because graphite has the same structure as the hexagonal Boron structure in MgB 2 . We added carbon impurities of graphite, C 60 , and open-ended carbon nano tube respectively to MgB 2 conductors made by powder in tube ex-situ process