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

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 ZT ∼ 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.