Large thermoelectric figure of merit at high temperature in Czochralski-grown clathrate Ba8Ga16Ge30 -: art. no. 023708

The Czochralski method was used to grow a 46-mm-long crystal of the Ba8Ga16Ge30 clathrate, which was cut into disks that were evaluated for thermoelectric performance. The Seebeck coefficient and electrical and thermal conductivities all showed evidence of a transition from extrinsic to intrinsic behavior in the range of 600-900 K. The corresponding figure of merit (ZT) was found to be a record high of 1.35 at 900 K and with an extrapolated maximum of 1.63 at 1100 K. This makes the Ba8Ga16Ge30 clathrate an exceptionally strong candidate for medium and high-temperature thermoelectric applications. (c) 2006 American Institute of Physics.