Alloying Cr2/3Te in AgCrSe2 compound for improving thermoelectrics.

AgCrSe₂, which crystallizes in alternative layers of Ag⁺ and CrSe₂⁻ octahedral structure, has shown great potential as good thermoelectric material due to its unique ultralow lattice thermal conductivity. In this work, compound Cr_2/3Te is alloyed with the matrix Ag_0.97CrSe₂ and the carrier concentration ranges within 10¹⁸–10²⁰ cm⁻³, enabling a reliable assessment of transport properties based on single parabolic band model at room temperature. Moreover, homogeneous nanoprecipitate is observed in the matrix for high Cr_2/3Te content samples, which leads to the scattering of main heat carrier of long-wavelength phonons, and thus a slight reduction of lattice thermal conductivity (∼0.3 W/m K) compared with intrinsic AgCrSe₂. Combined with the optimized carrier concentration and the low lattice thermal conductivity, a figure of merit zT of 0.6 at 650 K is achieved, exceeding other reported AgCrSe₂ systems, demonstrating the current Ag_0.97CrSe₂(Cr_2/3Te)_x materials as good potential thermoelectrics. [ABSTRACT FROM AUTHOR]