The general pre-requisite condition for the stable existence of 2n interface between phases is that ______?

For a stable interface between phases (e.g., solid-liquid, liquid-liquid), the Gibbs free energy of formation must be negative, indicating that the formation of the interface is thermodynamically favorable. A positive free energy would make the interface unstable, while zero would indicate a neutral condition. This principle is fundamental in phase stability and interfacial chemistry.