Fabrication and thermoelectric properties of Mg2Si1−xSnx (0 ≤ x ≤ 1.0) solid solutions by solid state reaction and spark plasma sintering

Mg2Si1−xSnx (0 ≤ x ≤ 1.0) thermoelectric materials have been prepared by solid state reaction and spark plasma sintering (SPS) techniques. Effects of the solid solution on phase structures and thermoelectric properties are investigated. X-ray diffraction (XRD) patterns show that Mg2Si1−xSnx (0 ≤ x ≤ 1.0) solid solutions have been primarily formed after solid state reaction, and enhanced by the spark plasma sintering. The microstructures of fractured surface and the change of lattice constants for samples show the homogeneous solid solutions are well formed by SPS. The thermoelectric properties of Mg2Si1−xSnx are all sensitive to Sn content. The addition of Sn significantly decreases thermal conductivity (κ), increases the electrical conductivity (σ), and reduces the absolute Seebeck coefficient (α). When x = 0.2, the highest figure of merit (ZT) of 0.1 is obtained at about 490 K, which is twice as high as that of pure Mg2Si.