A low-temperature thermoelectric transport study of non-stoichiometric AgSbTe

In recent times, considerable attention has been given to examining the impact of micro/nanostructure on the thermoelectric characteristics of nonstoichiometric AgSbTe. The present investigation employed direct melting of elements that produced p-type AgSbTe with spontaneous nanostructuring due to cation ordering. The product predominantly features an Ag-deficient AgSbTe phase with monoclinic AgTe nanoprecipitates and exhibits a degenerate semiconductor-like behavior with an energy band gap of 0.15 eV. A Seebeck coefficient of 251 μV K and a power factor of 741 μW m K at near ambient temperature are attained with this composition. The variable range hopping (VRH) and linear magnetoresistance (LMR) confirmed that the low-temperature transport followed a VRH between the localized states. The composition also exhibited glass like thermal conductivity of 0.2 W m K arising from phonon scattering at all-scale hierarchical structures that led to a high ZT of 1.1 at room temperature. The direct melted ingots show a high relative density of ∼97%, Vickers hardness H of ∼108.5 kgf mm, and excellent thermal stability, making them an attractive choice for TEGs.