Silicides
Magnesium silicide Mg2Si
Magnesium silicide is a low cost and environmentally friendly, medium temperature thermoelectric material with working temperature range T = 500÷800 K, characterized by low density (ρ = 1.99 g·cm3), comparatively low thermal expansion coefficient (αc = 7.5·10-6 K-1) and relatively high hardness (Tw = 4500 MN·m-2). Mentioned parameters are very encouraging, especially much lower density in relation to other known medium temperature thermoelectric materials, such as PbTe (ρ = 8.16 g·cm-3), CoSb3 (ρ = 7.63 g·cm-3, or AgSbTe2 and AgSbSe2 alloys (respectively ρ = 7.12 g·cm-3, ρ = 6.69 g·cm-3).
Fig. 1. Anti-fluorite structure of magnesium silicide Mg2Si [1].
Fig. 2. Lithium doped magnesium silicide Mg2-xLixSi [2].
Fig. 3. Temperature dependence of ZT parameter for Mg2Si1−xBix samples with a measurement error equal to 10% [3].
Taking into account all the above properties, magnesium silicide could be considered in widespread application, in particular thermoelectric modules of TEG generators.