Substitution-induced pinning in MgB 2 superconductor doped with SiC nano-particles

By doping MgB 2 superconductor with SiC nano-particles, we have successfully introduced pinning sites directly into the crystal lattice of MgB 2 grains (intra-grain pinning). It became possible due to the combination of counter-balanced Si and C co-substitution for B, leading to a large number of intra-granular dislocations and the dispersed nano-size impurities induced by the substitution. The magnetic field dependence of the critical current density was significantly improved in a wide temperature range, whereas the transition temperature in the sample MgB 2 (SiC) x having x = 0.34, the highest doping level prepared, dropped only by 2.6 K.