Formation of inhomogeneous micro-scale pores attributed ultralow κlat and concurrent enhancement of thermoelectric performance in p-type Bi0.5Sb1.5Te3 alloys

In the background of enhancing thermoelectric (TE) figure of merit of solid-state materials, the introduction of porous structure can significantly decrease lattice thermal conductivity by intensifying phonon scattering at the inhomogeneous microscale pores. Herein, we developed a porous structure in Cu0.07Bi0.5Sb1.5Te3 compounds by utilizing PVA as the pore former, and systematically studied its effect on thermoelectric properties. The results revealed that the reduction in thermal conductivity (similar to 28%) was greater than the decrease in electrical conductivity (similar to 17%) with increasing porosity, indicating long-wavelength phonon scattering was enhanced at micro-scale pores. Consequently, a peak zT of 1.342 at 400 K, and a zT(avg) of 1.254 in the temperature range of 300-500 K and an eta(max) of similar to 9.4% at Delta T = 200 K were achieved in the porous sample (10.58%), which all are higher than that of dense sample. The hardness and compressive strength of the porous samples were significantly higher than commercial zone melting ingots. The proposed methodology is a cost-effective and efficient way of producing high-performance TE devices with good mechanical stability for real life practical applications. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The introduction of a porous structure can significantly decrease thermal conductivity and enhance phonon scattering effects, thus improving thermoelectric performance; Development of a porous structure in Cu0.07Bi0.5Sb1.5Te3 compounds showed superior TE properties compared to dense samples; The porous samples exhibited advantages in thermoelectric performance, hardness, and compressive strength.