Silver vacancy concentration engineering leading to the ultralow lattice thermal conductivity and improved thermoelectric performance of Ag 1-x InTe 2

AgInTe 2 compound has not received enough recognition in thermoelectrics, possibly due to the fact that the presence of Te vacancy (V Te ) and antisite defect of In at Ag site (In Ag ) degrades its electrical conductivity. In this work, we prepared the Ag 1- x InTe 2 compounds with substoichiometric amounts of Ag and observed an ultralow lattice thermal conductivity ( κ L = 0.1 Wm −1 K −1 ) for the sample at x = 0.15 and 814 K. This leads to more than 2-fold enhancement in the ZT value (ZT = 0.62) compared to the pristine AgInTe 2 . In addition, we have traced the origin of the untralow κ L using the Callaway model. The results attained in this work suggest that the engineering of the silver vacancy (V Ag ) concentration is still an effective way to manipulate the thermoelectric performance of AgInTe 2 , realized by the increased point defects and modified crystal structure distortion as the V Ag concentration increases.