Silicide materials: Thermoelectric, mechanical properties, and durability for Mg-Si and Mn-Si

Abstract To further enhance the thermoelectric (TE) capability of Mg- and Mn-silicides in order to realize a practical TE power generator (TEG), sufficiently low resistance ohmic contacts at the interface between the electrode material and the Mg- and Mn-silicides are needed. In this chapter, we report a method to obtain thermally stable electrodes on Mg- and Mn-silicides. We also have examined the interface profile, the thermal diffusion, and alloy formation and discussed these observations in terms of the behavior of the electrical resistance. TE devices need to be as long lasting as possible during operation over a mid-temperature range of 600–900 K. This requires an improvement in the mechanical properties. By incorporating SiC nanoparticles, we have substantially improved these, especially the fracture toughness of the material. The process of introducing the nanoparticles into the silicide matrix and the amount introduced have been optimized to minimize any deterioration in the TE properties. Using first-principles calculations, we can predict the physical properties of silicide materials, such as their electric and thermoelectric properties, based on the calculation of their electronic states. The calculations are now feasible even for systems with complicated microscopic structures containing impurities, defects, and interfaces.