Electrochemical stability, physical, and electronic properties of thermally pre-formed oxide compared to artificially sputtered oxide on Fe thin films in aqueous chloride. (1st July 2021)

• Record Type: Journal Article
• Authors: Han, Junsoo; Wartenberg, Marlene G.; Chan, Ho Lun; Derby, Benjamin K.; Li, Nan; Scully, John R.
• Is Part Of: Corrosion science. Volume 186(2021)
• Publication Date: 2021-07-01
• Subjects: Fe oxide -- Sputtered oxide -- Corrosion -- Electronic defect density -- EIS -- XPS; Corrosion and anti-corrosives -- Periodicals; 620.11223
• DOI: 10.1016/j.corsci.2021.109456
• Languages: English
• ISSNs: 0010-938X

Abstract

Highlights: Investigate electrochemical properties of a model sputtered oxide as a surrogate to a reactor material oxide. Sputtered oxide showed an enhanced corrosion resistance than the thermally formed oxide in Cl − containing electrolytes. Significantly increased electronic defect density for the thermally oxidized Fe compared with sputtered oxide. Abstract: The electrochemical stability and corrosion behavior of the thermally pre-oxidized and sputter deposited variant of an oxide single-crystalline Fe thin film were compared. Thermal oxides formed Fe2 O3 over an inner layer of Fe3 O4 while the sputtered oxides were found to have grown Fe3 O4 instead of the target stoichiometry of Fe2 O3 . Oxide films of both types were stable in pH = 9.3 borate buffer solution, however, were altered in pH = 9.3, 0.1 M NaCl solution in the case of thermally pre-oxidized Fe thin film. The stability of the oxide differed in pH = 4, 0.1 M NaCl where sputtered Fe films were more stable against acidic chemical dissolution than the thermally formed Fe oxide film. These differences were traced by AC/DC electrochemical analysis including electronic defect densities, and molecular identity characterized by ex-situ X-ray photoelectron spectroscopy.