Synergistic effect of indium nano-inclusions to enhance interface phonon scattering in polycrystalline SnSe for thermoelectric applications

Abstract

Tin selenide (SnSe) has attracted more interest as thermoelectric material due to the anharmonic nature and record high ZT of 2.6 for single crystalline SnSe. The polycrystalline SnSe has better mechanical properties compared with single crystalline materials. Due to poor electrical properties and inhomogeneous phase segregation limit the use of SnSe as a thermoelectric material. In this work, indium incorporated SnSe has been prepared by vacuum melting technique followed by ball milling process. X-ray diffraction (XRD) and High resolution micrography (HRTEM) confirmed the pure phase formation along with the high crystalline nature of the samples. Presence of indium has been confirmed using X-ray photoelectron spectroscopy (XPS). Indium leads to the formation of nano inclusions, which was confirmed using electron probe micro analyser (EPMA) technique. These nano inclusions enhanced the phonon scattering and reduced the thermal conductivity. Thus, SnSe incorporated with 10 wt% indium gives a minimum thermal conductivity of around 0.48 W/mK at 615 K.