Resolving Bismuth Enriched Grain Boundaries in Thermoelectric Materials

Thermoelectric materials have versatile applications from energy generation to solid state cooling. Bismuth Telluride (BiTe) and its alloys are the most commonly used thermoelectric materials for Peltier cooling devices.
Shown here is a map of Silver-Lead-Bismuth-Telluride (AgPb18BiTe20) with Bismuth segregation at grain boundaries. Pb and Te are evenly distributed in the material, whereas local fluctuation in Ag concentration is visible in the mini maps. Pb and Bi have strong overlaps in the EDS spectra. The automated peak fitting and deconvolution algorithm of ESPRIT 2 was able to distinguish between Pb and Bi peaks with strong overlaps.

Bismuth segregation in AgPbTeBi thermoelectric materials
EDS spectra showing strong overlaps of Pb (green) and Bi (yellow) peaks