ICT2014 Abstracts

In the recent years, many efforts were made for generation of nano features in bulk thermoelectric materials for enhancement of the thermoelectric figure merit via the reduction of the lattice thermal conductivity. Taking into account that thermoelectric direct converters from heat to electricity, without involving of any moving parts, exhibit a major stability advantage for long-term operation, compared to many other competing conversion methods, the stability of nano-featured bulk thermoelectric materials is a major issue for consideration.

In the current research, an alternative, thermodynamic nano-features generation approach in bulk IV-VI based thermoelectric materials, was considered, using controlled phase separation conditions according to the relevant phase diagrams. Specific systems showing a miscibility gap, including the PbTe-GeTe and PbTe-PbS systems, were heat treated under various required conditions for promoting spinodal decomposition and nucleation and growth reactions. High ZT values of up to 2.2 were obtained due to combined optimal doping and sub-micron phases' decomposition features. Such features were found as thermodynamically stable under long-term investigation at temperatures up to 400^oC, resulting in almost unchanged figure of merit values after the various investigated heat treatment durations.