Overview: The emf method as a source of experimental thermodynamic data

The use of galvanic cells to determine the thermodynamic properties of metallic or ceramic materials from electromotive force (emf) measurements is described. Two basic types of the method are distinguished: those employing liquid electrolytes and those based on solid ion-conducting electrolytes. Liquid electrolytes can be aqueous solutions, but for thermodynamic measurements in metallic materials molten salt mixtures with the addition of the corresponding charge-carrying ion are mostly used. Solid electrolytes applied in the thermochemistry of alloys and ceramic materials are usually based on oxides (such as ZrO2) as oxygen conductors, on ββ- or β″β″-alumina as sodium ion conductors (with the possibility to exchange sodium ions by other cations), or on fluorides (such as CaF2) as fluoride conductors. For all these cases, typical cell arrangements and corresponding examples from the literature are given.