ICT2014 Abstracts

We have applied this synthesis process to, among others, Bi₂Te₃, Bi₂Se₃, Cu₂Se, Cu₂SnSe₃, half-Heusler alloys, lead chalcogenides, skutterudites, and magnesium silicides for the first time. we obtained a single phase material with thermoelectric properties better or on par with materials prepared by the traditional routes of synthesis. This is due to the purification process associated with the passage of a reaction zone through the ingot and the maintenance of exact stoichiometry on account of a very short duration of synthesis and minimal exposure to oxygen. Moreover, we found that the criterion often quoted in the literature as the necessary precondition for self-sustainability of the combustion wave, T_ad › 1800 K is not universal and certainly not applicable to thermoelectric compound semiconductors. Instead, we offer new empirically-based criterion, T_ad/T_m,L > 1, i.e., the adiabatic temperature must be high enough to melt the lower melting point component. This new criterion covers all materials synthesized by SHS, including the high temperature refractory compounds for which the T_ad > 1800 K criterion was originally developed. Our work opens a new avenue for ultra-fast, low cost, mass production fabrication of efficient thermoelectric materials and the new insight into the combustion process greatly broadens the scope of materials that can be successfully synthesized by SHS processing.