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Sulphur segregation on free and oxidized NiAl(001)
Author(s) -
Rivoaland L.,
Maurice V.,
Bacos M.P.,
Marcus P.
Publication year - 2002
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.1326
Subject(s) - nial , x ray photoelectron spectroscopy , auger electron spectroscopy , feal , amorphous solid , aluminium , sulfur , materials science , low energy electron diffraction , metal , diffusion , analytical chemistry (journal) , crystallography , chemistry , electron diffraction , chemical engineering , intermetallic , diffraction , metallurgy , alloy , thermodynamics , physics , optics , chromatography , nuclear physics , engineering
Auger electron spectroscopy (AES), low‐energy electron diffraction (LEED) and X‐ray photoelectron spectroscopy (XPS) data on the segregation of sulphur at the surface of an NiAl(001) single crystal and at the interface with alumina thin films are reported. The results show that sulphur segregates at the free metallic surface. The amount of segregated sulphur decreases with increasing aluminium content of the surface. Although the segregation of aluminium is favoured thermodynamically, segregation kinetics and diffusion coefficients measured at 700, 750, 800 and 850°C [ D = 0.15 exp(−2 18 000/ RT )] show that the segregation of sulphur is favoured kinetically. Saturation of the metallic surface with an amorphous alumina layer formed at room temperature blocks the segregation of sulphur. However, in the initial stages of oxidation at 950°C where the transient θ alumina grows by cationic transport and injection of vacancies at the interface, sulphur segregates at the interface between the alumina thin films and the metallic substrate as measured by XPS. Copyright © 2002 John Wiley & Sons, Ltd.