SURFACE PHASE-TRANSITIONS AT CHARGED INTERFACES PROBLEMS IN THEIR EXPERIMENTAL AND THEORETICAL INVESTIGATION

The possibility of a phase transition to proceed reversibility within an electrified interface is examined. It is shown that the inhomogenei ty of a real interface and in particular the existence of a diffuse la yer is likely to put serious obstacles for a phase transition to take place reversibly, especially when the controlled electrical variable i s the electrode potential. However, their occurrence cannot be ruled o ut. Reversible phase transitions may be more easily observed if the el ectrode charge density is used as the independent electrical variable. Irreversible transitions are also expected under charge density contr olled conditions. In this case negative capacities might be observed. Finally, the various problems about the clarification of the nature of a phase transition experimentally and the implications to their theor etical description are also discussed.