SPECTROSCOPIC STUDIES OF CHALCOGENIDE GLASS MEMBRANES OF CHEMICAL SENSORS - LOCAL-STRUCTURE AND IONIC RESPONSE

Enhanced chemical durability, suitable and variable transport characteristics, actually unlimited ability to be doped or modified thus changing their structure and properties suggest an application of non-crystalline chalcogenides and chalcohalides (bulk glasses and thin films) as promising membrane materials for conventional chemical sensors and chemical microsensors selective to heavy metal ions in various liquid media. Furthermore, they can be used as convenient model materials for a better understanding of fundamentals of the ionic response. Relationships between composition, local structure, ionic and electronic transport phenomena, on the one hand, and surface-ion exchange and ionic response, on the other hand, are the main topics to be discussed in the present contribution. Mossbauer spectroscopy and surface spectroscopy studies allow important information to be obtained concerning the short- and medium-range order in the glasses as well as surface processes occurring at the glass/solution interface. It will be shown that different microstructural organizations of the glass membrane (glass-network topology, chemical and structural states of the components, etc.) lead to drastically different transport, exchange and sensor properties. Structural and mechanistic studies of this kind are, therefore, extremely important for further development and optimization of chalcogenide glass chemical sensors.