AN IMPROVED THERMODYNAMIC CALCULATION OF INTERFACE PROPERTIES AND ITS APPLICATION FOR LOW-INDEX AND POLYCRYSTALLINE SURFACES OF PTNI

Some years ago a new thermodynamic theory of interfaces was proposed [L.Z. Mezey, Surf. Sci. 162 (1985) 510]. Its general conditions of the thermodynamic equilibrium state were solved in a simplified two-sublayer model for binary solids in a first approximation (MTCIP-1A: modem thermodynamic calculation of interface properties - first approximation), and applied to several cases including surface interactions with environmental (e.g. oxygen) atoms and the segregation of non-metallic interstitial solutes. That simplified theory is further developed here by a new description of the anisotropy of the surface free energy and of the lattice distortion and its relaxation at the surface (for dilute solutions). This new version is shown to be the first theory in agreement with the experimental results showing Ni segregation on (Pt)Ni(110). Similar agreement is outlined for (100), (111) and polycrystalline surfaces of (Pt)Ni and for Pt(Ni).