Large Seebeck Coefficients of Fe2TiSn and Fe2TiSi: First-Principles Study

We systematically investigated the electronic structure of full-Heusler alloys with valence electron counts per formula unit of 24 by using first-principles calculation. We found various semiconducting full-Heusler alloys with flat bands at the bottom of the conduction band. In terms of low toxicity and low cost, we focused on semiconducting Fe2TiSn and Fe2TiSi. We found that they could possess high thermoelectric power ranging from -300 to -160 mu V/K with the electron-carrier concentrations from 1 x 10(20) to 1 x 10(21) cm(-3) around room temperature. Our results also suggest that Fe2TiSn1-xSix alloy has a great potential to realize a higher figure-of-merit (ZT) value, compared to conventional full-Heusler alloys. (C) 2013 The Japan Society of Applied Physics