Synthesis and characterization of Mg2Si based thermoelectric materials for high temperature applications

The possibility to convert waste heat into electricity, such as in combustion devices, is attracting great attention on thermoelectric materials. With this view, high temperature materials are necessary to increase the thermoelectric conversion efficiency, which is proportional to Carnot efficiency. Doped Mg2Si are very attractive thermoelectric materials for intermediate to high temperature applications, presenting high ZT values, low cost, light weight and low toxicity of constituents. With this view, a study on Mg2Si based thermoelectric materials will be presented in this work. In particular, this work is focused on the synthesis of several doped Mg2Si carbon nanostructure composites, since several attempts of employing carbon nanostructure for enhancing the thermoelectrical properties of other kinds of materials were reported in literature. The powders were prepared by ball milling and the TE pellet were produced by Spark Plasma Sintering. All samples were characterized by FE-SEM, EDS and XRD analyses. Moreover, the thermopower and the electrical conductivity of the samples are presented. Thermogravimetrical analyses were carried out in order to evaluate the magnesium silicide stability as a function of temperature in humidified air.