2013 Volume 60 Issue 8 Pages 354-359
Dimagnesium silicide (Mg2Si) is a promising n – type thermoelectric compound suitable for thermoelectric power generation using waste heat of intermediate temperature range (600 − 900 K). However, there are two problems in making the Mg2Si compound. One is difficulty in synthesizing the compound due to ease of Mg evaporation in fusion, resulting in existence of non-reacting Si. Another is difficulty in sintering the synthesized powder. In order to overcome the two problems, we synthesized the Mg2Si compound on Mg – rich state by the liquid-solid phase reaction and sintered the synthesized powder by the pulse discharge sintering (PDS). The influences of Mg/Si ratio and B addition on the sinterability and the thermoelectric properties of the synthesized Mg2Si compounds were investigated. The sinterability of the synthesized Mg2Si compounds were improved by the increase of Mg amount. And, electrical resistivities of sintered samples were decreased by B addition. Therefore, thermoelectric properties were strongly affected by both Mg/Si ratio and B addition. The sample synthesized with feed amount of Mg of 67.00 at% and additive amount of B of 1.0 at% had the maximum dimensionless figure of merit of about 0.39 at 773 K.
