Effects of polycarbosilane doping on the superconductivity and microstructure of MgB2

The effect of polycarbosilane (PCS) doping on the superconducting properties and microstructure of MgB2 bulk has been studied in this paper. It is found that the lattice parameter a and the superconducting transition temperature decrease with increase of the doping level. However, the critical current density Jc is significantly enhanced and the Jc(B) properties are improved at low temperature. Microstructure analysis indicates that a lot of Mg2Si nanoparticles, including those 5?10?nm in size, and some lattice defects induced by the PCS doping exist inside the PCS doped MgB2 samples, which may be the main reason for the enhancement of the flux pinning property.