Investigation of the substitution of mercury by silver in Ag2S-HgS-GeS2 glasses: Macroscopic, electrical and vibrational properties

Abstract

The evolution of structure and physical properties was investigated in the (Ag₂S)_x(HgS)_50-x(GeS₂)₅₀ system. It was found that the density increases with increasing silver sulfide. The DSC data show a non-monotonic change of the glass transition temperature, T_g, from 243 °C (x = 0) to 301 °C (x = 50) with the minimum at 231 °C for x = 10 sample. The dual structure of HgS, which consists of the presence of dimorphic tetrahedral and chain forms of HgS, is found to be responsible for the non-monotonic change of the T_g. An increase in silver content leads to a significant enhancement of ionic conductivity from ∼10⁻¹⁴ S.cm⁻¹ (x = 0) to ∼10⁻³ S.cm⁻¹ (x = 50). The gradual structural evaluation is evidenced by the disappearance of the main Raman feature at ≈300 cm⁻¹ related to the Hg-S stretching and the emergence of two contributions for silver-rich glasses at ≈370 cm⁻¹ and at ≈400 cm⁻¹.