About new criteria of component activities at the interface between two condensed phases

A simple thermodynamic approach based on the Adams–Guggenheim–Russanov method has been established to see the effects of an infinitesimal quantity of an impurity on the physico-chemical characteristics of the interface between two condensed binary phases in thermodynamic equilibrium. The impurity constitutes the first component. It has been established that only the knowledge of the properties of the constituents in their pure states allows one to qualitatively assess the influence of this impurity on the characteristics of the interface, and quantitatively assess the distribution of the impurity in the bulks of the two phases and at their interface.