Threefold enhancement of the thermoelectric figure of merit for pressure tuned Sr8Ga16Ge30

Abstract
Semiconducting germanium clathrates are thermoelectric materials with cage-like structures that exhibit “phonon glass, electron crystal” behavior. We report an improvement by at least a factor of 3 in the dimensionless thermoelectric figure of merit for the clathrate semiconductor Sr8Ga16Ge30 upon compression to 7 GPa. These results suggest that there is potential for further improving the thermoelectric properties of this material at ambient pressure by chemical or other methods.