Single crystals of type-VIII clathrate Ba8Ga16Sn 30 (BGS) with p- and n-type carriers were grown from Ga flux and Sn flux, respectively. With the increase of the initial flux amount, both the electrical resistivity ρ and the absolute value of the Seebeck coefficient α are decreased, indicative of effective carrier doping. In the optimally doped samples, the dimensionless thermoelectric figure of merit ZT has the maximum values of 1.0 and 0.9 at 450 K for p-and n-type samples, respectively. In aiming at further increase of the ZT value, Sb was substituted for Sn in BGS. It is found that the Ga content in the crystals unexpectedly increases with the increase of Sb content and thus the crystal composition is described as Ba 8Ga16+xSn30-x-ySby (x < 0.9, y < 0.9). The ZT value for the p-type sample with x = y = 0.7 has the maximum of 1.0 at around 480 K.
All Science Journal Classification (ASJC) codes
- Mechanics of Materials
- Mechanical Engineering
- Metals and Alloys
- Materials Chemistry