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**An improved thermodynamic calculation of interface properties and its application for low-index and polycrystalline surfaces of PtNi**

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L.Z. Mezey^{*} and W. Hofer

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Institut für Allgemeine Physik,
Technische Universität Wien, A-1040 Wien, Austria*

^{*}Institute of Physics, TU Budapest, H-1111 Budapest, Hungary
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*Surf. Sci. 269/270 (1992) 1135-1141*

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: modern
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 Pt(Ni).

Corresponding author: W. Hofer (hofer).