Preparation of polycrystalline bulk Mg2Si by using NaSi
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Recently, thermoelectric materials have been attracting attention in the field of effective energy saving by utilization of waste heat. Mg2Si and Mg2Si-based materials are expected to be used as an alternative to PbTe for application in thermoelectric devices in the temperature range from 500 to 800 K because of their high thermoelectric properties. Moreover, Mg2Si has the lowest density, i.e., 2.0 g/cm3, among thermoelectric materials and its constituent elements, i.e., Mg and Si, are abundant and nontoxic [1, 2, 3, 4]. According to the Mg–Si phase diagram presented by Okamoto et al. , Mg2Si is the only binary phase of this system and melts at 1354 K. Because the melting point of Mg2Si is close to the boiling point of Mg (1363 K) and the vaporization of Mg from the Mg–Si melt is significant around this temperature, preparation of Mg2Si polycrystalline bulk and single crystals from the Mg–Si melt has been performed under 0.2–0.4 MPa of inert gas to suppress Mg vaporization [6, 7, 8,...
KeywordsSpark Plasma Sinter Thermoelectric Property PbTe Seebeck Coefficient Compact Body
This work was supported in part by a Grant-in-Aid for Young Scientists (A) (20685015) from the Ministry of Education, Culture, Sports, Science and Technology.
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