Vacancy and anti-site disorder scattering in AgBiSe2 thermoelectrics

Abstract

AgBiSe₂ has recently been shown to exhibit promising thermoelectric properties due to the low intrinsic thermal conductivity, stemming from a large degree of lattice anharmonicity. While samples synthesized via solid-state routes usually exhibit n-type behavior, p-type transport is seen in samples based on solution synthetic routes possibly due to Ag vacancies. Using a combined approach of synchrotron diffraction, thermoelectric transport measurements and thermal transport modeling, we show the influence of synthetically induced Ag vacancies on the structure of AgBiSe₂ and the thermoelectric transport. We identify the degree of anti-site disorder of Ag and Bi due to the occurring phase transformation and the influence of the vacancy content on metal ordering. Additionally, we show that anti-site disorder and vacancies act as scattering centers for phonons, leading to enhanced point defect scattering in this interesting thermoelectric material.