Biomass-derived carbon doping to enhance the current carrying capacity and flux pinning of an isotopic Mg11B2 superconductor

Low activation isotopic boron (B-11) based magnesium diboride ((MgB2)-B-11) superconductors doped with biomass-derived activated carbon were synthesized using B-11 and magnesium powder via solid-state reaction. The effect of carbon doping on the lattice structure and superconducting properties of (MgB2)-B-11 bulks were evaluated using X-ray powder diffraction, high resolution transmission electron microscopy, scanning electron microscopy and magnetization measurements. Precise refinement of structural parameters indicates successful substitution of carbon in (MgB2)-B-11 bulks. The critical current density (J(c)) of carbon doped (MgB2)-B-11 synthesized at 650 degrees C was enhanced more than two times compared with the pure (MgB2)-B-11 bulk. Similar improvement was observed for the (MgB2)-B-11 bulks heat-treated at 800 degrees C. This enhancement is due to successful substitution of biomass-derived carbon with high surface area into (MgB2)-B-11 lattice. The flux pinning mechanism of pure and doped (MgB2)-B-11 bulks were investigated using the Dew-Hughes model. This study provides information regarding enhancement of the J(c) of low activation (MgB2)-B-11 superconductors suitable for next-generation fusion magnets. (C) 2022 Chongqing University. Publishing services provided by Elsevier B.V. on behalf of KeAi Communications Co. Ltd.