).
Earlier a general theory of solid surfaces was developed by one of us
(MTCIP: Modern Thermodynamic Calculation of Interface Properties).
A part of this theory describes the surface concentration profile for
the thermodynamic equilibrium state by a system of non-linear equations.
This system was solved in a first approximation for dilute mixtures and
applied to several bimetallic alloys, with reliable results in several
publications, even in the case of surface interactions with environmental
(oxygen) atoms.
Recently a much more detailed second approximation (MTCIP-2A) has been
developed, permitting - among other improvements - extension of the
description to more concentrated alloys as well. Its description is
under publication now, and is shortly outlined here, too.
Here we present calculated concentration profiles for the (100), (110)
and (111) surfaces of PtNi (for T=1120K). These profiles are in good
agreement with existing experimental values for all the surface
orientations and all the bulk concentrations; mostly the values are
within the experimental error. These results are discussed and compared
with other theoretical calculations, which - as it is known - can be
quite problematic for PtNi.
Corresponding author: W. Hofer (hofer).