Preparation and thermoelectric properties of quaternary bismuth telluride-indium selenide compound

Quaternary In-Se-Bi-Te compounds (7.5Bi(2)Te(3)-In(2)Se(3) and 7.5Bi(2)Te(3)-In(4)Se(3)) were prepared by water quenching and annealing, and the microstructures and thermoelectric properties were investigated. These materials were solidified to near-eutectic compositions in order to obtain micro-scale hetero-interfaces. The formation of sub-micrometer-scale lamellae layers of Bi(2)Te(3) and In-Se-Te compounds was observed. Through quenching, the 7.5Bi(2)Te(3)-In(2)Se(3) consisted of a Bi(2)Te(3) and In-Se-Te compound, while the 7.5Bi(2)Te(3)-In(4)Se(3) was composed of Bi(2)Te(3), BiTe, and In(4)Se(3) and In-Se-Te. Both the microstructure and the constituent phases changed after annealing. The reduction of thermal conductivities, as compared to that of bulk Bi(2)Te(3), was confirmed. This result can be attributed to the increased number of phase boundary areas. The size of the decomposed phase could be controlled by changing the parameters of the annealing process, which could further decrease the thermal conductivity. (C) 2011 Elsevier B.V. All rights reserved.