ISSN:
1618-2650
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Summary The chemical composition of free surfaces of solids (not interacting with the environmental atoms) depends on its bulk composition, on the temperature, on the time of annealing (in non-equilibrium states) and on surface orientation (in single crystals). Even in the relatively most simple case of “qualitatively” just predicting, which of the components of a dilute binary substitutional alloy composed of transitional metals segregates to its free surface, the present theories disagree with the experimental results in several cases. The problem, of course, gets even more complicated if the surface interacts with the environmental atoms (e.g. oxygen). Then environmental factors as e.g. the value of the oxygen partial pressure Po2 are as well among the variables determining the surface composition. A new theory, the MTCIP-1A (Modern Thermodynamic Calculation of Interface Properties — First Approximation) includes the description of that effect as well. Its applicability is shown here for a polycrystalline PtNi alloy with bulk content X(1) Ni=12 at % under non-oxidizing and oxidizing conditions. Our ISS (Ion Scattering Spectroscopy) results shown agree with the MTCIP-1A at both conditions (with Pt segregation in the first, while that of Ni in the second one). Some further examples of such agreement between theory and experiment are mentioned.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00321941
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