Influence of Aluminum Addition on Sinterability and Thermoelectric Properties of Mg₂Si Compound Prepared Using Liquid-solid Phase Reaction Method and Pulse Discharge Sintering

Abstract

Mg₂Si compound is a promising material available for thermoelectric power generation using waste heat of temperature range of 600 to 900 K. However, high vapor pressure of molten Mg makes difficulties in synthesis of Mg₂Si compound and in sintering. In order to overcome these problems, we synthesized the Mg₂Si compound under Mg–rich condition by the liquid-solid phase reaction and sintered the synthesized powder by the pulse discharge sintering. In this study, we attempted to add aluminum of 0−2.0 at.% to the Mg₂Si and investigated the influence of addition of aluminum on sinterability and thermoelectric properties. Addition of Al brought to improvement of the sinterability and reduction of the electrical resistivity. The 1.0 at.% Al–added sample had the maximum dimensionless figure of merit of 0.86 at 873K.