Effect of nano-SiC doping on the structure and superconducting properties of Mg(B_1-xC_x)₂

Carbon doping is studied in MgB₂ pellets during one-step synthesis by solid-state reaction, employing both undoped and carbon-doped boron with and without the addition of nano-SiC. The phase formation during the synthesis as a function of time was followed using powder X-ray diffraction and Rietveld refinement. The superconducting properties were characterized with a magnetometer to investigate doping-induced changes. Mg(B_1-xC_x)₂ is obtained with nano-precipitates and different compositions depending on the synthesis temperature. It is found that the addition of nano-SiC prevents the phase formation at low temperature (700°C). Nevertheless, the best superconducting properties are obtained for the sample treated at 900°C using simultaneously C and SiC, with a critical current density of 10⁵ A cm^-2 at 3 T and 20 K, named the 900-20-C-nanoSiC sample.