Band convergence strategy to improve thermoelectric performance in Ti-Doped AgSbTe2

Abstract

Abstract AgSbTe2 is one of promising material for waste heat recovery in the lower-medium (450–600 K) temperature range. However, its development is hindered by the formation of Ag2Te. In this study, we employed a mechanical alloying method to synthesize samples, significantly reducing the Ag2Te. Density functional theory (DFT) confirms that Ti doping in AgSbTe2 samples leads to the involvement of multiple valence bands in transport and decrease the energy offset between the light valence band and the primary valence band. Therefore, the Seebeck coefficient (S) increases from the value of 245 μV/K in Ag1.05SbTe2 to 270 μV/K in the Ag1.05Sb0.98Ti0.02Te2 samples at 473 K. A maximum ZT value of ∼1.28 at 523 K and an average ZT value of ∼0.97 within 323–548 K are obtained in Ag1.05Sb0.99Ti0.01Te2.