A comparative study on the effects of n C, n SiC and BRH on the structural and superconducting properties of MgB2 PIT wires

A comparative study on the structural and superconducting properties of MgB2 Powder-In-Tube (PIT) wires doped with various weight percentage of nano carbon (n C), nano SiC (n SiC) and Burned Rice Husk (BRH) has been carried out. X-Ray diffraction patterns of n SiC and BRH doped samples showed peaks of Mg2Si which is a useful intragrain inclusion for flux pinning. The Lattice parameter 'a' decreased with increasing doping concentration for all the doped samples, the maximum being for n C, indicating C substitution for B. The Full Width at Half Maximum (FWHM) of (hk0) peaks of all samples increased with doping. Doping caused a reduction in grain size and SEM images showed tightly packed smaller grains containing hexagonal crystallites in all the three types of doped samples. All the dopants reduced the transition temperature of the undoped sample and the effect was severe for n C doping. Unlike the pure sample, the transport critical current density (JC) of the doped samples didn't fall rapidly at high fields; but retained large fractions depending on the dopants. The best results were obtained for n SiC and BRH doped samples with BRH closely matching the performance of n SiC. Improvement in critical current density for these samples was an order higher than the undoped sample at 4.2 K and 8 T.