Flux Pinning and Levitation Stability in SiC-Doped MgB₂ Superconductors Prepared by Spark Plasma Sintering

In this study, MgB2 bulk superconductors doped with 0-20% wt SiC were synthesized via in-situ Spark Plasma Sintering (SPS), and their physical and magnetic properties were systematically investigated. Resistivity-temperature (rho-T) and H-T phase diagram analyses revealed that while increasing SiC content reduces the transition temperature (Tc) and broadens the transition width (Delta Tc), it simultaneously enhances flux pinning and magnetic stability through a dual mechanism. Specifically, partial decomposition of SiC at 850 degrees C leads to carbon substitution in the MgB2 lattice, increasing electron scattering and creating effective lattice distortions, while residual SiC nanoparticles and Mg2Si secondary phases act as volumetric and intergranular pinning centers. Critical current density (Jc) and normalized pinning force (Fp/Fp,max) analyses confirmed strong pinning performance, particularly at 10-15% wt doping levels, where both Jc and Hirr were maximized. Vertical and lateral levitation force measurements under zero-field-cooled (ZFC) and field-cooled (FC) conditions further demonstrated that the 15% wt sample exhibited the most stable flux trapping capacity, maintaining strong magnetic response even near the superconducting transition. Notably, the sample with 5% wt SiC addition exhibited the highest critical current density of 1.08 x 106 A/cm2 at 20 K under self-field, confirming the effectiveness of optimized doping for high-performance applications.These results confirm that controlled SiC doping and SPS processing effectively tailor MgB2 bulk superconductors for high-performance magnetic and levitation applications.