The fast silver ion conducting solid-state electrolytes for deriving thermodynamic data

The electromotive force (EMF) method was describedand some characteristic examples from the past and recent literature were reviewed.The important experimental procedures for a successful measurement of an EMF ofdifferent galvanic cells at a certain temperature and determination of thethermodynamic properties of chemical compounds from the obtained EMF valueswere described. A typical galvanic cell arrangement in a furnace was presented.The two most common types of AgI-based solid electrolytes, AgI and RbAg₄I₅,were discussed in detail. The ionic conduction mechanisms and the applicationof the solid electrolytes in the EMF cells were described. In this work, wehave also conducted EMF measurements using the fast Ag+ ion conductingsolid-state electrolyte. The solid-state electrolyte Ag₃GeS₃I glass and thecathode material Ag₄HgSe₂I₂ were synthesized and electrochemical cell (-)graphite | Ag | Ag₃GeS₃Iglass | Ag₄HgSe₂I₂ | graphite(+) was assembled to measure the activity of Ag in thequaternary phase. The extremely low values of activity of silver in Ag₄HgSe₂I₂in the temperature range 412–482 K indicate that Ag₄HgSe₂I₂ has superionic property. The obtained results and the determined thermodynamic values arepresented and discussed.