Rare-earth silicides: the promising candidates for thermoelectric applications at near room temperature

Metal silicides are considered promising candidates for thermoelectric applications thanks to the advantages of low toxicity and high stability. The most well-known silicide is Mg2Si which exhibits high thermoelectric efficiency, determined by the dimensionless figure of merit (zT) at the temperature range of 600 to 800 K. Other conventional silicides such as FeSi2, CrSi2 Ru2Si3, and higher manganese silicides have their highest zT values at temperatures higher than 800 K. However, there are limited known silicide-based thermoelectric materials operating at near room temperature. Here, we focused on rare-Earth (RE) silicides, exhibiting special behaviors of heavy fermion or mixed valence. Such behaviors cause an uncommonly large Seebeck coefficient and thermoelectric power factor for metal at low temperatures, which are potential advantages for thermoelectric applications at low temperatures. Thus, we will review several reports on RE silicide-based thermoelectric materials and our recent work on Yb(Si1-x Ge x )(2-delta ), which is considered a promising thermoelectric material at near room temperature.