High-temperature thermoelectric properties of non-stoichiometric Ag1 − xInTe2 with chalcopyrite structure

Our group has revealed that AgGaTe2 with the chalcopyrite structure exhibits relatively high thermoelectric (TE) figure of merit (ZT) when it has a deviation of Ag content from the stoichiometry. The maximum ZT value of 0.77 was obtained for Ag0.95GaTe2 at 850 K. On the other hand, the TE properties of AgInTe2 with the same chalcopyrite structure with AgGaTe2 have not been investigated. In the present study, we examined the high-temperature TE properties of AgInTe2 with the composition of Ag1 − xInTe2 (x = 0, 0.01, 0.03, and 0.05). The deviation of Ag content from stoichiometry slightly enhanced the ZT value. The maximum ZT value was 0.07 at 600 K obtained in the samples of x = 0.03 and 0.05.

► The polycrystalline bulk samples of Ag1 − xInTe2 (x = 0, 0.01, 0.03, and 0.05) with high density were successfully synthesized.
► Both the electrical resistivity and the absolute values of the Seebeck coefficient decreased with decreasing Ag content, implying that the reduction of Ag increased the carrier concentration of AgInTe2.
► The thermal conductivity values were relatively low, and decreased with decreasing Ag content, likely due to the phonon scattering by the lattice defect of the Ag site in AgInTe2.
► The samples of x = 0.03 and 0.05 exhibited similar and the best thermoelectric figure of merit; the maximum value was 0.07 at 600 K.