SILVER ION SENSORS BASED ON AG-AS-SE-TE GLASSES .2. SURFACE STUDIES AND TRACER MEASUREMENTS OF ION RESPONSE

The 110mAg exchange between Ag-As-Se-Te glasses and silver nitrate solutions has been investigated. Energetic and kinetic parameters of interfacial ionic processes have been found to be close to the corresponding values of the bulk ion transport. XPS study of chalcogenide glass membranes has revealed the oxidation of telluride to tellurium dioxide at the glass surface after soaking in silver nitrate solution. Therefore, the dramatic deterioration of the response of Te-rich glass sensors is a consequence of at least three factors: (a) the enhancement of hole conductivity and electronic exchange current density at the glass/solution interface; (b) the decrease of ionic conductivity and of the rate of interfacial ionic processes; (c) telluride oxidation at the membrane surface, which is the most perceptible for Te-rich glasses. © 1990.