Nanostructure-Enhanced Bulk Thermoelectric Materials

The objective of this proposal is to develop and implement methodologies for new bulk thermoelectric materials that incorporate nanostructural elements to significantly increase the thermoelectric figure of merit, ZT, by way of phonon boundary scattering providing enhanced fuel economy via waste-heat to electrical energy conversion as well as provide stand-alone power from either intentional fuel sources or naturally occurring heat harvesting circumstances. Three primary methods will be used to develop nanostructures within a target thermoelectric alloy (AgPbmSbTe2+m) with the goal of developing a commercially realizable bulk material methodology resulting in high ZT thermoelectric devices. The unique cubic AgPbmSbTe2+m (LAST) structural identity can be exploited to produce nanostructural components that will act as phonon scattering sites within the bulk material. Tellurex's continuing work on the LAST system indicates that structural grain size reduction may be brought to nanoscale through rapid quenching and advanced mechanical powder processing techniques. A scaled sintering regimen will also be developed and employed to induce nanoscale boundary growth providing phonon boundary scattering. These processes will be used singularly and in combined strategies to determine the method resulting in the highest ZT and provide the focus for Phase II and Phase III development.