Thermoelectric properties of Ag[sub 2]Te[sub x]Se[sub 1−x] ternary compounds

Abstract

A low lattice thermal conductivity is one of the conditions to achieve a high thermoelectric figure of merit, Z=α2σ/(κl+κe), where α is the Seebeck coefficient, σ is the electrical conductivity and κl, κe are the lattice and electronic contributions to thermal conductivity respectively. Silver chalcogenides binary compounds exhibit very low lattice thermal conductivity coupled with high electrical characteristics leading to relatively high thermoelectric figure of merit (e.g. for β-Ag2Se we obtained Z≈2.6 10−3 K−1 at 300 K). The effect of alloying can normally lead to further decrease the lattice thermal conductivity. In this paper we report on the results of low temperature transport properties of Ag2TexSe1−x (0⩽x⩽0.5) ternary compounds in the temperature range from 70K to 300K. The effect of substitutional alloying on their electrical properties is discussed. The thermoelectric figures of merit at 300K are estimated.