The doping effect of activated carbon on the superconducting properties ofMgB2 tapes

Abstract

Activated carbon doped MgB2 tapes were prepared by the in situ powder-in-tube method. The phase,crystal structure, microstructure, resistance, etc were analyzed by x-raydiffraction (XRD), scanning electron microscopy (SEM) and a physical propertiesmeasurement system (PPMS). It was found that the irreversibility field(Hirr) and uppercritical field (Hc2) wereenhanced when MgB2 samples were doped with activated carbon, and the magnetic field dependence of the critical currentdensity (Jc) was improved significantly. For the 5% activated carbon dopedMgB2 tapes,the Jc value was nearly eight times higher than that of undoped tapes at 13 T (4.2 K). Onthe other hand, the activated carbon doping level has a significant effect on theJc valuesof MgB2 tapes. When the doping level is higher than 5%, theJc values decrease with increasing activated carbon doping level.