Silver sulfide based glasses (I). Glass forming regions, structure and ionic conduction of glasses in GeS 2Ag 2S and GeS 2Ag 2SAgI systems

Abstract

Ag 2S forms with GeS 2 stable glasses over a wide range of compositions (0–55% Ag 2S mol%). In the same system, more complex glasses obtained by dissolving silver iodide have been synthesized with up to 50 mol% AgI. Raman spectra are presented and a vibrational assignment in terms of bridging and non-bridging sulfur has been made. The electrical conductivity of these glasses has been measured over a temperature range (−50°C− + 50°C) and for various compositions by the complex impedance diagram method. At 25°C, the conductivity reached a maximum value of 6 × 10 −3 Ω −1 cm −1. Whatever the glass used, the same limit value of conductivity (σ − 10 su−2 Ω −1 cm −1 ) and activation energy ( E σ ⋍ 0.25 eV ) are obtained for the highest content of silver iodide. A conduction mechanism is proposed.