Phase formation sequences and mechanism of MgB2 superconductor with minor Sn doping

Abstract

Combined with thermal analysis and phase identification, the phase formation of Sn-doped MgB2 superconductor during the sintering process were systematically investigated. As compared to the sintering of MgB2, the first exothermal peak occurs at a lower temperature, which suggests the accelerated formation of MgB2 after minor Sn doping. The sintering process of minor Sn-doped MgB2 orderly underwent the melting of Sn, the reaction between Mg and Sn, the eutectic Mg–Sn reaction, the solid–solid Mg–B reaction, the melting of Mg, the liquid–solid Mg–B reaction and the Sn precipitation. Based on the phase formation mechanism, MgB2 bulks was successfully synthesized by Sn-activated sintering at 600 °C for only 5 h, exhibiting a dramatic decrease in the sintering time compared to the sintering of undoped MgB2.