Influence of FeSe doping on superconducting properties of MgB2 by hybrid microwave method

The effect of FeSe doping on the physical properties of MgB2 is studied. Bulk samples of the FeSe doped MgB2 with weight ratio x(FeSe:MgB2)=0%,3%,7%and10% were prepared by hybrid microwave method. It is proved that FeSe is not stable together with MgB2. Fe2+ enters into MgB2 lattice, some Mg2+ and Se2− are combined into the new impurity compound MgSe. The superconducting transition temperature (Tc) slightly decreased with increasing doping content of FeSe from R-T and M-T curves, which results from the substitution of Mg2+ by Fe2+ in the MgB2 lattice. The Jc increase slightly with the FeSe doping content increasing from 3 wt % to 10 wt %, which results from the increasing MgSe impurity pinning centers.