Extruded Bismuth-Telluride-Based n-Type Alloys for Waste Heat Thermoelectric Recovery Applications

Thermoelectric (TE) generator modules for a number of waste heat recovery applications are required to operate between room temperature and 500 K, a temperature range for which the composition of bismuth-telluride-based alloys needs to be adjusted to optimize performance. In particular n-type alloys do not perform as well as p-type and require a more systematic study. We have produced, by mechanical alloying followed by hot extrusion, (Bi(1-x)Sbx)(2) (Te(1-y)Sey)(3) alloys, within the range 0 <= x; y <= 0.1; with fixed carrier concentration (n = 2 x 10(19) cm(-3)) to optimize their TE performance in the temperature range 300 K to 420 K. The optimum composition has been identified to be x = 0.03 and y = 0.07; which is very close to the composition that also maximizes the ratio of the electron mobility to the lattice component of the thermal conductivity. The optimized alloy performance can be further increased by adjusting the carrier concentration.