First-principles study on thermal transport properties of GeBi2Te4, SnBi2Te4, and PbBi2Te4 compounds

Despite extensive studies on Bi2Te3, a comprehensive understanding of thermal transport properties of its pseudo-binary ATe-Bi2Te3 analogs (A = Ge, Sn, Pb) remains elusive. In this study, we present first-principles investigations into the lattice thermal conductivity of ABi2Te4 compounds by including both population and coherence of phonons. The T−1 temperature-dependence is observed. We reveal that GeBi2Te4 exhibits intrinsically ultralow lattice thermal conductivity of 0.87 and 0.58 W m−1 K−1 at 300 and 500 K, respectively, which is primarily due to strong lattice anharmonicity originating from optical modes with exceptionally high Grüneisen parameters. SnBi2Te4 and PbBi2Te4 also show low thermal conductivity at room temperature, which is further reduced effectively to <1 W m−1 K−1 at 300 K via nanostructure engineering through scattering phonons with long mean free path.