(Invited) Thermoelectric Materials and Modules for High Temperature Application

A layered misfit Ca 3 Co 4 O 9 shows high thermoelectric efficiency at high temperature in air. Thermoelectric modules using p-type Ca 3 Co 4 O 9 and n-type CaMnO 3 have been produced. The maximum power density reaches 4.3 kW/m 2 at 973 K of the heat source temperature. A new n-type silicide material, Mn 3 Si 4 Al 2 has been discovered. The dimensionless thermoelectric figure of merit reaches 0.21 at 773 K. This silicide shows good oxidation resistance at 873 K in air. Thermoelectric modules consisting of 64 pairs of legs have been fabricated using MnSi 1.7 and Mn 3 Si 4 Al 2 as p- and n-type legs, respectively. Output power reaches 9.4 W corresponding to 2.3 kW/m 2 of power density at 873 K of the heat source temperature in air.