Theoretical study on the change of thermoelectric properties by substitution of group 4 elements in Fe2TiSn

Abstract

In this study, substitution effects of group 4 elements in Fe2TiSn thermoelectric material are studied by using density functional theory (DFT) and semi-classical Boltzmann transport theory. All of the substitution elements showed the most thermodynamic preference for the Sn site, and these substitutions for Fe2TiSn did not give much influence in the stability and mechanical property of Fe2TiSn. e2TiSn[Formula: see text]Pb[Formula: see text], and thermoelectric calculations showed the prominence of [Formula: see text]-type on [Formula: see text]-type dopingin these materials. The highest Seebeck coefficients of these compounds were −148, −228, −165 and −120 [Formula: see text]V/K for [Formula: see text]-type of Fe2TiSn, Fe2TiSn[Formula: see text]Si[Formula: see text], Fe2TiSn[Formula: see text]Ge[Formula: see text] and Fe2TiSn[Formula: see text]Pb[Formula: see text], respectively. The results showed that Si and Ge partial substitutions for Fe2TiSn could be the effective methods to enhance the thermoelectric property, and the maximum dimensionless figure of merit (ZT) at room temperature reached about 0.7 ([Formula: see text]cm[Formula: see text] [Formula: see text]-type doping concentration) in Fe2TiSn[Formula: see text]Si[Formula: see text] and 0.6 ([Formula: see text]cm[Formula: see text] [Formula: see text]-type doping concentration) in Fe2TiSn[Formula: see text]Ge[Formula: see text].