Enhanced Thermoelectric Performance by Strong Phonon Scattering at the Heterogeneous Interfaces of the Mg₂Sn/Mg₃Sb₂ High-Content Nanocomposite

Abstract

Nano approaches are practical strategies to boost the thermoelectric figure of merit due to the strong phonon scattering from the grain boundaries and nanoinclusions. Here, we have reported a strong phonon scattering at the heterogeneous interfaces of Mg₂Sn/Mg₃Sb₂ high-content nanocomposites (HCnCs). As a result, a significantly reduced lattice thermal conductivity of 1.09 W m^-1 K^-1 was observed in the equimolar Mg₂Sn/Mg₃Sb₂ HCnC, 80% lower than pure Mg₂Sn and 25% lower than pure Mg₃Sb₂. As a result, a high <i>ZT</i> ∼ 1.13 at 773 K was achieved in the Mg₂Sn/Mg₃Sb₂ HCnC. Furthermore, various defects, including solid solutions, nanoinclusions, and misfit dislocations, were observed in both the Mg₃Sb₂ phase and the Mg₂Sn phase through the microstructure characterization.