Microstructure and thermoelectrical investigations of an N-type magnesium-silicon-tin alloy

An N-type Mg2Si0.3875Sn0.6Sb0.0125 powder, directly prepared by mechanical alloying from the raw elements, has been sintered by spark plasma sintering. TEM observations enabled to detect nano-sized inclusions (diameter around 13 nm, 1.9 × 109 inclusions/mm2) dispersed in the bulk of individual grains constituting the sintered polycrystal (grain size around 450 nm). These inclusions (enriched in Sn and impoverished in Mg) are thought to scatter lattice vibrations, leading to a dimensionless-thermoelectrical figure of merit (ZT) around 0.85 at 500 °C.