Thermoelectric Properties of Sn-Containing Mg2Si Nanostructures

The thermoelectric performance of Mg2Si-containing nanomaterials are predicted based on density-functional and Boltzmann’s transport theories. The investigated materials are Mg2Si1–xSnx thin films with x = 0.125 and x = 0.625, and (Mg2Si)1–x (Mg2Sn)x (x = 0.4 and x = 0.6) in the form of either superlattices or assembled nanosticks. The calculated properties (Seebeck coefficient S, electrical conductivity σ, and power factor S2σ) are compared with those of bulk Mg2Si1–xSnx. It is shown that the thin films outperform the bulk materials at low temperature (350 K) as they exhibit a higher Seebeck coefficient and comparable electrical conductivity. A low electrical conductivity at 900 K is responsible for the counter-performance of the films. Superlattices are attractive structures as p-doped materials at both low charge carrier concentration/high temperature and high charge carrier concentration/high temperature. The assembled nanosticks are interesting materials at low carrier concentration/low temperature only.