Novel Thermoelectric Materials Based on Clathrates

The phenomenon of thermoelectricity is attributed to the interconversion of thermal and electrical forms of energy. We developed a new class of bulk thermoelectric materials based on clathrates with a three-dimensional framework comprised of oversized transition metal-phosphorus polyhedral cages that encapsulate guest cations. Transition metal-based clathrates have the following advantages over conventional Si-, Ge-, and Sn-based clathrates: a larger variety of framework topologies and a higher tunability of the electronic properties via framework substitutions. The correlation between the crystal structure, distribution of the metal and phosphorus atoms over the clathrate framework and thermoelectric properties will be discussed.