The acceleration of low-temperature sintering of MgB2 bulks with high critical density by minor Sn doping

In the present study, MgB2 bulk was successfully synthesized by Sn-activated sintering at 600 degrees C for just 5 h, exhibiting a dramatic decrease in the sintering time compared to that required for sintering an undoped sample at the same temperature. According to the thermal analysis, a local Mg-Sn liquid formed first during the sintering process and then this prompted the diffusion of Mg into B. As a result, the solid-solid reaction between Mg and B was accelerated and the phase formation of MgB2 was completely achieved at low temperature. The complete formation of the MgB2 phase results in a high J(c) of the Sn-doped samples sintered at low temperature. Besides this, the small MgB2 grains and nanoimpurities in the sintered samples also contributed to the good performance as regards J(c).