Microstructure and Thermoelectric Properties of Mg 2 Si/Si Thermoelectric Eutectic Crystals Grown by Rapid Cooling Process

ABSTRACT Eutectic crystals, including Mg 2 Si and Si phases, are grown from the melt at the eutectic point using the vertical Bridgman method in a carbon crucible in three stages: ZrO 2 , Al 2 O 3 , and W. The eutectic morphology became finer in the ZrO 2 , Al 2 O 3 , and W stages, revealing that the stage with higher heat dissipation resulted in a finer eutectic morphology. However, the rapid cooling process decreased the relative density of the eutectic crystals because of the formation of voids, which reduced the electrical conductivity. The power factor is improved in the temperature range of 200–400°C by the change in stages from ZrO 2 to Al 2 O 3 .