New bulk Materials for Thermoelectric Power Generation: Clathrates and Complex Antimonides

Thermoelectric power generation is foreseen to play a much larger role in the near future, considering the need for alternative energies because of declining natural resources as well as the increasing efficiency of thermoelectric materials. The latter is a consequence of the discoveries of new materials as well as of improvements of established materials by, for example, nanostructuring or band structure engineering. Within this review, two major classes of high-temperature thermoelectrics are presented: clathrates formed by silicides and germanides, and complex antimonides including but not limited to the Filled skutterudites. The clathrates and the skutterudites are cage compounds that exhibit low thermal conductivity, reportedly related to the rattling effect of the guest atoms, whereas the other antimonides achieve low thermal conductivity via defects or simply via the high complexity of their crystal structures.