Influence of powder size on thermoelectric properties of p-type 25% Bi2Te3-75%Sb2Te3 alloys fabricated using gas-atomization and spark-plasma sintering

Herein, we report our work on large-scale production (2 kg/min) of BiSbTe alloy powders by gas atomization and spark-plasma sintering. We tried to optimize the fundamental transport parameters (carrier concentration, mobility, effective mass, and thermal conductivity) for improved thermoelectric performance of p-type Bi2Te3 by selecting different size ranges of powder particles. The Seebeck coefficient values were greatly enhanced (by 52%) due to increase in effective mass, and thermal conductivity was decreased (by 36%) using the <30 mu m powder spark-plasma sintered sample (compared with GA sample) due to phonon scattering at the grain boundary. However, the 32-75 mu m powder is preferable for attaining a high ZT value due to its high thermoelectric quality factor (beta). The highest ZT value obtained was 1.23 at 350 K for the 32-75 mu m powder bulk samples. This was an improvement of similar to 23% compared to the GA sample. The average ZT(av) of 1.15 in the temperature range 300-400 K, enables the alloy to be suitable for low temperature applications. (C) 2016 Elsevier B.V. All rights reserved.