Influence of production parameters on the thermoelectric properties of Mg/sub 2/Si

According to the literature, Mg/sub 2/Si possesses good thermoelectric properties, However, no easy fabrication process for this material is known to date, In this paper we present a new production route based on modified mechanical alloying and hot uniaxial pressing that leads to samples free from oxides, Comparison is made with samples produced by a conventional powder metallurgical process leading to the contamination with MgO. The samples were examined by differential scanning calorimetry, laser flash-, Hall-, and Seebeck-measurements. The results show that the samples free from oxides have an improved thermal stability, a higher thermal conductivity and a much higher Hall mobility. Thus, the thermoelectric figure of merit z could be improved by a factor of 3.5. Additionally, the electronic transport behaviour of the oxide-free samples was examined. It can be explained by the contribution of an additional conduction band.