Preparation of Mg2Si-based thermoelectric materials using waste silicon sludge as a source material

Abstract

Sb-doped Mg2Si was prepared using waste silicon sludge via a liquid-solid phase reaction and pulse-current sintering. Two types of Si sludge were used as a silicon source. One is an unwashed Si sludge, and the other is Si sludge washed with a water-based agent. In the samples prepared from unwashed Si sludge, Mg2Si, Mg, and MgO phases existed. In the case of samples prepared from the washed Si sludge, the X-ray diffraction patterns showed almost a single phase, although a small MgO phase remained.The thermoelectric properties of Mg2Si prepared from the washed Si sludge were improved by control of weighed composition and carrier concentration. The obtained maximum figure of merit of this study was 0.66 in the samples prepared from the washed Si sludge, which is equivalent to materials prepared from reagent Si with identical carrier concentration.