Microwave direct synthesis and thermoelectric properties of Mg2Si by solid-state reaction

In order to reduce the oxidation and volatilization caused by Mg element in the traditional methods for synthesizing Mg2Si compounds, Mg2Si thermoelectric materials were prepared by solid state reaction and microwave radiation techniques. Structure and phase composition of the materials were investigated by X-ray diffraction. The electrical conductivity, Seebeck coefficient and thermal conductivity were measured as a function of temperature from 300 to 700 K. It is found that high purity Mg2Si powders can be obtained with excessive content of 8% Mg from the stoichiometric Mg2Si at 853 K and 2.5 kW for 30 min. A maximum dimensionless figure of merit, ZT, of about 0.13 was obtained for Mg2Si at 600 K.