Properties of Superconductor by Doping Impurity of SiC, Graphite, , and C Nano-Tube

Since MgB₂ 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 MgB₂ is enhanced by doping of SiC nano powder, and Fujii reported MgB₂ superconductor made by the powder-in-tube in-situ process using MgH₂ 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 MgH₂ as a precursor powder increased to 23 T by the SiC doping. These results show MgB₂ 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 MgB₂. We added carbon impurities of graphite, C₆₀, and open-ended carbon nano tube respectively to MgB₂ conductors made by powder in tube ex-situ process