Influence of FeSe doping on superconducting properties of MgB_2 by hybrid microwave method

Abstract

The effect of FeSe doping on the physical properties of MgB_2 is studied. Bulk samples of the FeSe doped MgB_2 with weight ratio x (FeSe:MgB_2) = 0%, 3%, 7%, and 10% were prepared by hybrid microwave method. It is proved that FeSe is not stable together with MgB_2. Fe^(2+) enters into MgB_2 lattice, some Mg^(2+) and Se^(2−) are combined into the new impurity compound MgSe. The superconducting transition temperature (T_c) slightly decreased with increasing doping content of FeSe from R-T and M-T curves, which results from the substitution of Mg^(2+) by Fe^(2+) in the MgB_2 lattice. The J_c increase slightly with the FeSe doping content increasing from 3 wt % to 10 wt %, which results from the increasing MgSe impurity pinning centers.

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