A low-temperature thermoelectric transport study of non-stoichiometric AgSbTe 2 .

In recent times, considerable attention has been given to examining the impact of micro/nanostructure on the thermoelectric characteristics of nonstoichiometric AgSbTe ₂ . The present investigation employed direct melting of elements that produced p-type AgSbTe ₂ with spontaneous nanostructuring due to cation ordering. The product predominantly features an Ag-deficient Ag _0.927 Sb _1.07 Te _2.005 phase with monoclinic Ag ₂ Te nanoprecipitates and exhibits a degenerate semiconductor-like behavior with an energy band gap of 0.15 eV. A Seebeck coefficient of 251 μV K ^-1 and a power factor of 741 μW m ^-1 K ^-2 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 ^-1 K ^-1 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 _v of ∼108.5 kgf mm ^-2 , and excellent thermal stability, making them an attractive choice for TEGs.