Anharmonic atomic dynamics and thermal transport in SnTe with stoichiometric defects

Abstract

IV-VI chalcogenides, such as SnTe, are promising for thermoelectric applications due to their structural similarity with conventional PbTe, which is widely used in thermoelectric power generation and environment friendliness. The intrinsic Sn vacancies in SnTe are important in governing the thermal conductivity. This study examines the role of Sn vacancies in influencing the behavior of phonons and lattice thermal conductivity in SnTe. Advanced computational techniques are used to analyze phonon dispersion, spectral energy density, and their impact on thermal transport. The results shed light on how vacancies affect specific phonon modes, providing insights into the mechanisms behind the remarkably low thermal conductivity of this material. Our results demonstrate that Sn vacancies in SnTe significantly reduce thermal transport by damping optic and high-energy acoustic phonon modes. The calculated lattice thermal conductivity accurately matches estimates from experimental data for SnTe and Sn0.9Te, explaining the observed glassy thermal conductivity behavior in the latter. The insights obtained from large-scale molecular dynamics simulations will help better understand the origin of ultralow thermal conductivity, even in simple structure compounds, and help design materials for thermoelectric applications.