Electrochemically and UHV-grown passive layers on Ni(100): a comparison by AC impedance, XPS, LEED, and HREELS

The electrochemical, spectroscopic, and structural properties of passive layers on Ni(100) grown either electrochemically in aqueous 10 mM HClO sub 4 or by dosing with gaseous oxygen in ultrahigh vacuum (UHV) were compared using a UHV-electrochemical transfer system equipped for X-ray photoemission...

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Bibliographic Details
Published in:Journal of the Electrochemical Society 1989-09, Vol.136 (9), p.2498-2506
Main Authors: WAGNER, F. T, MOYLAN, T. E
Format: Article
Language:English
Subjects:
Applied sciences
Corrosion
Corrosion mechanisms
Cross-disciplinary physics: materials science
rheology
Exact sciences and technology
Materials science
Metals, semimetals and alloys
Metals. Metallurgy
Physics
Specific materials
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Summary:The electrochemical, spectroscopic, and structural properties of passive layers on Ni(100) grown either electrochemically in aqueous 10 mM HClO sub 4 or by dosing with gaseous oxygen in ultrahigh vacuum (UHV) were compared using a UHV-electrochemical transfer system equipped for X-ray photoemission spectroscopy (XPS), low energy electron diffraction (LEED), and high resolution electron energy loss spectroscopy (HREELS). The two films share a similar component of several layers of anhydrous NiO, but the electrochemical layer also contains smaller amounts of additional forms of O. The elements of structural order in the two NiO films differ in epitaxial relationships with the substrate. Similar ac impedance behaviors and dc passive current densities are seen when the clean and UHV-oxidized Ni(100) surfaces are contacted with electrolyte at the passive potential; but 6 mC/cm exp 2 of anodic charge must be passed to reach a steady passive state on the clean surface, while 0.8 mC/cm exp 2 suffices on the UHV-oxidized surface. Comparison with the very well-defined UHV oxide allows improved precision in the characterization of the passive layer. , . 52 ref.--AA
ISSN:0013-4651
1945-7111
DOI:10.1149/1.2097445