Enhanced Thermoelectric Properties of Mg2Sn-Mg3Sb2 Nanocomposites by Tailoring Matrix/Inclusion Interface toward Energy Harvesting Applications

Abstract

Nanocomposites have been long exploited for achieving balanced material properties. Here, we synthesized nominal (Mg2Sn0.85Sb0.15)1–x-(Mg3Sb2)x (x = 0–0.15) nanocomposites, achieving a significant reduction of the lattice thermal conductivity of Mg2Sn0.85Sb0.15 from 2.03 Wm–1K–1 to 1.38 Wm–1K–1 due to phonon scattering by VMg point defects, Mg3Sb2 nanoparticles, and heterogeneous interfaces. Hence, a significantly enhanced thermoelectric figure of merit, ZT, is achieved. At 773 K, the sample of x = 0.075 reaches a ZT of 1.4, corresponding to a 14% enhancement compared to the Mg2Sn0.85Sb0.15 (x = 0) sample. The strategy of introducing heterogeneous structures has important implications for reducing thermal conductivity for other solid-solution thermoelectric systems.