Improved thermal stability of thermoelectric Mg2Si0.4Sn0.6

Abstract Mg2Si0.4Sn0.6 is a low cost thermoelectric (TE) material suitable for making high-efficiency TE modules. However, the high reactivity of this material demands proper surface protection at the operating temperatures. Towards this, SiO2 aerogel encapsulation was investigated in this work. The bulk thermoelectric samples fabricated from spark plasma sintered pellets were covered with aerogel and isothermally treated between 673 and 823 K for 12 h under ambient air. The bare specimens, which decomposed completely into MgO, SnO2, Si, and Sn after isothermal treatment at 673 K, was found to be stable even up to 823 K under aerogel encapsulation. Thus, the above findings demonstrate that the SiO2 aerogel encapsulation of Mg2Si0.4Sn0.6 can successfully be used up to 823 K without noticeable degradation of its TE performance.