Optimum dopant content of n-type 95% Bi₂Te₃ + 5% Bi₂Se₃ compounds fabricated by gas atomization and extrusion process

The n-type (Bi₂Te₃-Bi₂Se₃) compound was newly fabricated by gas atomization and hot extrusion, which is considered to be a mass production technique of this alloy. The aim of this research is to analyze the effect of the amount of dopant on the thermoelectric properties for n-type 95% Bi₂Te₃ + 5% Bi₂Se₃ compounds. The microstructure of extruded bar shows homogeneous and fine distribution of grains through full length due to dynamic recrystallizaiton during hot extrusion. The absolute values of Seebeck coefficient for the compounds doped 0.02, 0.04, 0.07 and 0.1 wt.% SbI₃ are 219.9, 175, 147.7 and 146.7 μV/K, respectively. The electrical resistivity (ρ) is highest at 0.02 wt.% SbI₃, while lowest is at 0.1 wt.% SbI₃. The compound with 0.04 wt.% SbI₃ shows the highest power factor among the four; different dopant contents because of the relative high Seebeck coefficient and the low electrical resistivity.