Effect of Chemical Composition on the Thermoelectric Properties of n-Type Bi2Te3 Alloys Fabricated by Gas Atomization and Hot Extrusion

In this research, n-type (Bi2Te3)1−x(Bi2Se3)x-based thermoelectric (TE) materials were produced through a gas atomization process, and subsequently hot extruded with an extrusion ratio of 10:1 at 400 °C. The effect of chemical composition on TE properties was investigated. The microstructure of all extruded bars showed a homogeneous and fine distribution of grains due to the dynamic recrystallization during the hot extrusion process. With increasing Bi2Te3 content, from 0.85 to 0.90, both electrical resistivity and Seebeck coefficient values were increased. The maximum figure of merit (ZT) 0.673 was obtained at room temperature for (Bi2Te3)0.90(Bi2Se3)0.10 alloys due to them exhibiting higher seebeck coefficient and lower thermal conductivity than other compositions.