Thermoelectric Properties of Bi0.5Sb1.5Te3 Prepared by Liquid-Phase Growth Using a Sliding Boat

A liquid-phase growth process using a graphite sliding boat was applied for synthesis of p-type Bi0.5Sb1.5Te3. The process lasted only 60 min, including rapid heating for melting, boat-sliding, and cooling. Thick sheets and bars of 1 mm and 2 mm in thickness having preferable crystal orientation for thermoelectric conversion were successfully prepared by the process. Control of carrier concentration was attempted through addition of excess tellurium (1 mass% to 10 mass%) to optimize the thermoelectric properties of the material. The Hall carrier concentration was found to be decreased by addition of excess tellurium. The electrical resistivity and Seebeck coefficient varied depending on the carrier concentration. As a result, the maximum observed power factor near 300 K was 4.4 × 10−3 W/K2m, with corresponding Hall carrier concentration of 4.6 × 1025 m−3. Thus, thermoelectric properties were controllable by addition of excess tellurium, and a large power factor was thus obtained through a simple and short process.