Magnetoelectric properties of MgB2 superconductor by SiC doping.

Effect of SiC, as carbon source doping, by diffusion method on the lattice parameter, critical temperature (Tc) and critical current density (Jc) has been studied. The broadening of full width at half maximum (FWHM) values in XRD patterns with increasing of the doping level indicates smaller grains and imperfect MgB2 crystallinity, whereas the carbon substitution into the boron site was confirmed by the shrinkage of the lattice parameter a. Despite of lower Tc's, Jcs of the doped samples are higher than the undoped sample over 4 T at 20 K and over 7 T at 5 K, respectively. MgB2 with the 10 % of SiC doping showed the highest Jc with the value of 105 A/cm2 at 5 K and 4 T while the 2.5% SiC doped sample showed 7 factor of Jc enhancement compared to pristine sample at 20 K and 4.5 T. Jc enhancement by different doping level at respective temperature suggests, impurities such as Mg2Si, MgB2C2 and MgO play a significant role in 20 K while carbon substitution effect dominances the flux pinning in 5 K. Our results also demonstrate that flux pinning and the Jc can be tailored for various applications depending on the operating temperature and external magnetic field. [ABSTRACT FROM PUBLISHER]