Processing and Characterization of Charcoal Added Bulk MgB2 Superconductor

Abstract

In this study, we focus on methods to further improve the flux pinning and critical current density (J c) of disk shaped MgB2 bulk superconductors by a comparative study with locally obtained charcoal at optimized processing conditions. The doping of charcoal was varied at 0, 0.2, 0.4 and 0.6 wt%. Bulk MgB2 samples were produced by in-situ solid state reaction in Ar gas and ambient pressures at 775 °C, employing high purity of Mg metal and nano B powder mixed in a fixed ratio of Mg:B = 1:2 and optimal conditions. The phase has been investigated by X-ray diffractometer (XRD). The effects of the dopants on superconducting properties especially the field dependence of J c have been determined by superconducting quantum interference device (SQUID) and critical temperature (T c). Measurements of the magnetic susceptibility showed sharp superconducting transitions (ΔT c ∼ 1 K). J c at self-field and 20 K was determined to be ∼280 and 467 kA/cm2 for the 0 and 0.4 wt% charcoal added samples respectively. The structural and superconducting results were correlated with the addition of charcoal in the final product.