Tunable microstructures and improved thermoelectric performance of Mg2(Si0.4−xSbxSn0.6) solid solutions

• The Mg2(Si0.4−xSbxSn0.6) (0≤x≤0.025) solid solutions were prepared by an induction melting and SPS method.
• The unique multiple nanostructures containing nanoscale precipitates and mesoscale grains are formed by the non-equilibrium preparing technique.
• The samples with existence of microstructures formation can be controlled by melt spinning technique combined with spark plasma sintering method.
• The multiply nanostructures result in decreasing of lattice thermal conductivities with the nanoscale precipitates having the size of 20–30nm
• The dimensionless figure of merit ZT was significantly improved and the maximum value reaches 1.30 at 773 K.

The single-phase n-type Mg2(Si0.4−xSbxSn0.6) (0≤x≤0.025) solid solutions were prepared by an induction melting and Spark Plasma Sintering method using buck of Magnesium, Silicon, Tin and Antimony. The unique multiple nanostructures of samples containing nanoscale precipitates and mesoscale grains are formed by the non-equilibrium preparing technique, resulting in remarkably decreasing of lattice thermal conductivities, particularly for samples with the nanoscale precipitates having the size of 20–30 nm. Meanwhile, the electrical properties were increased by Sb-doping. The thermoelectric performance of Sb doped samples with the nanostructures are remarkably improved, and the dimensionless figure of ZT for Mg2(Si0.38Sb0.02Sn0.6) sample shows highest value of 1.30 at 773 K, which is very much higher than that of the non-doped sample.