Silver tellurides: Structural, elastic, and optical properties of AgTe and Ag2Te

Abstract

In recent years, Ag-Te systems have attracted much attention because of their unique properties of relatively large magnetoresistance and high electrical conductivity. In this article, we consider stoichiometric and silver-excess phases of silver telluride and report the structural, elastic, electronic, and optical properties obtained with density functional theory. Orthorhombic AgTe and monoclinic Ag2Te exhibit nearly isotropic bulk and shear moduli, although the Young's modulus exhibits large anisotropy along crystalline axes. The calculated electronic properties show AgTe to be a direct band-gap semiconductor with high electron mobility and Ag2Te to be nearly metallic. A larger anisotropy in both the real and the imaginary part of the dielectric function is predicted for AgTe relative to Ag2Te, with the plasmon energies being 17.2 eV. The calculated results thus establish a structure-property relationship in defect-free silver tellurides.