Thermoelectric properties of non-stoichiometric AgSbTe2 based alloys with a small amount of GeTe addition

Abstract

The (Ag0.366Sb0.558Te)1−x(GeTe)x (0 < x ⩽ 8%) solid solutions were prepared and the thermoelectric properties were presented from 300 to 600 K. The Seebeck coefficient decreased with an increase in GeTe content x, while the electrical conductivity and thermal conductivity followed the opposite trend, indicating the carrier concentration increased monotonically with GeTe content. The thermal conductivity showed almost no temperature dependence. Lorenz number was calculated under consideration of the two carrier conduction mechanism, and the thermal conductivity was mainly from lattice conduction. The calculated lattice thermal conductivity increased monotonically with GeTe content, suggesting that unharmonic umklapp scattering dominates thermal conduction in this material system. By rough estimation it is demonstrated that the increasing lattice thermal conductivity after alloying is a result of the increase in the Debye temperature and the decrease in the Grüneisen parameter.