Self-assembling of atomic vacancies at an oxide/intermetallic alloy interface

Maurice, Vincent; Despert, G.; Zanna, Sandrine; Bacos, M.-P.; Marcus, Philippe

doi:10.1038/nmat1203

Cited by 106 publications

(80 citation statements)

References 20 publications

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“…Neutral chemistry.-In NC1 solutions, the concentrations of chloride ions and sulfate ions were 0.65 mol/L and 0.15 mol/L respectively; the effect of chloride ions on the passive film is the dominant one though it is known that a small amount of sulfates may mitigate the detrimental effect of chlorides. The adsorption of chloride ions into a passive film may increase the cation vacancy concentration in two possible ways: (1) Chlorides may enhance the transfer of metal ions from the oxide to the electrolyte; 62 (2) Chlorides may fill anion vacancies according to the point defect model (PDM). 29,30,33 As a consequence of mechanism (1), the concentration of surface cation vacancies increases in solutions containing chloride.…”

Section: Effects Of Ph On Mechanisms Of Sulfur-induced Passivity Degrmentioning

confidence: 99%

“…If these vacancies penetrate into the metal phase at a rate slower than their transport through the oxide, they accumulate at the metal-oxide interface. Marcus et al 62 found evidence for the formation and self-assembly of clusters of oxygen vacancies at a metal-oxide interface. When an oxide grows on the surface of a metal, after the first monolayer is formed, transport processes within the oxide become a factor.…”

Section: Effects Of Ph On Mechanisms Of Sulfur-induced Passivity Degrmentioning

confidence: 99%

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pH Effect on Sulfur-Induced Passivity Degradation of Alloy 800 in Simulated Crevice Chemistries

Xia

Zhu

Behnamian

et al. 2014

J. Electrochem. Soc.

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The effects of pH on sulfur-induced passivity degradation of Alloy 800 in simulated crevice chemistries were evaluated using electrochemical impedance spectroscopy (EIS), secondary ion mass spectroscopy (SIMS), and Mott-Schottky analysis methods. Experimental results reveal that the detrimental effect of impurities containing sulfur at the reduced or intermediate oxidation level (S x ) on the passivity of Alloy 800 depends significantly on the solution pH. In neutral crevice (NC) chemistry containing chloride ions, the S x obstructs the healing process during repassivation, retards the dehydration reaction and also incorporates H, -OH and S into the passive film. However, the detrimental effect of S x is insignificant in an alkaline crevice (AKC) solution due to a change in surface adsorption and surface charge. Impurities containing sulfur at the reduced or intermediate oxidation level would cause Alloy 800 to lose its passivity and become active in an acidic crevice (AC) chemistry. Experimental evidence also indicates that the solution pH alters the semiconductor type of the surface film -from n-type in NC solution to p-type in AKC solution.

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Section: Effects Of Ph On Mechanisms Of Sulfur-induced Passivity Degrmentioning

confidence: 99%

Section: Effects Of Ph On Mechanisms Of Sulfur-induced Passivity Degrmentioning

confidence: 99%

pH Effect on Sulfur-Induced Passivity Degradation of Alloy 800 in Simulated Crevice Chemistries

Xia

Zhu

Behnamian

et al. 2014

J. Electrochem. Soc.

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show abstract

“…52 Compared to natural oxidation, the rate of oxygen intake into the oxide film in photon-assisted growth is significantly increased due to an activation-barrier reduction. The enhanced oxidation kinetics due to elimination of the chemisorption barrier as well as lowered activation-energy barrier for ionic migration is responsible for the increased uptake of oxygen in the near-surface region of the passive-oxide film.…”

Section: G Corrosion Resistance Of Ultrathin Oxidesmentioning

confidence: 99%

Compositional tuning of ultrathin surface oxides on metal and alloy substrates using photons: Dynamic simulations and experiments

et al. 2010

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We report on the ability to modify the structure and composition of ultrathin oxides grown on Ni and Ni-Al alloy surfaces at room temperature utilizing photon illumination. We find that the nickel-oxide formation is enhanced in the case of oxidation under photo-excitation. The enhanced oxidation kinetics of nickel in 5% Ni-Al alloy is corroborated by experimental and simulation studies of natural and photon-assisted oxide growth on pure Ni͑100͒ surfaces. In case of pure Ni substrates, combined x-ray photoelectron spectroscopy analysis, and atomic force microscope current mapping support the deterministic role of the structure of nickel passiveoxide films on their nanoscale corrosion resistance. Atomistic simulations involving dynamic charge transfer predict that the applied electric field overcomes the activation-energy barrier for ionic migration, leading to enhanced oxygen incorporation into the oxide, enabling us to tune the mixed-oxide composition at atomic length scales. Atomic scale control of ultrathin oxide structure and morphology in the case of pure substrates as well as compositional tuning of complex oxide in the case of alloys leads to excellent passivity as verified from potentiodynamic polarization experiments.

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“…A viable approach for the synthesis of ultrathin oxide films is based on the selective oxidation of suitable bimetallic alloys [18][19][20][21][22]. The prototypical example is an ultrathin alumina film on the NiAl(110) substrate [18,23], which has been widely used as a support in model catalytic studies [1,[24][25][26].…”

Section: Introductionmentioning

confidence: 99%

From two- to three-dimensional alumina: Interface templated films and formation of γ−Al2O3 (111) nuclei

et al. 2017

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Oxide thin films are of fundamental importance due to their applications in materials science, optics, corrosion protection, catalysis, and microelectronics. A multistep oxidation procedure is employed to precisely tune the alumina (Al 2 O 3 ) thickness on a NiAl(110) alloy from two atomic bilayers to 1.5 nm. Structural changes are analyzed with x-ray photoelectron diffraction and low-energy electron diffraction. The long-range order does not relate to any bulk structure and is imposed by the crystallized interface. The large unit cell formed at the interface persists in thicker films. In contrast, the local order changes at a thickness above 0.5 nm from the complex structure of this prelayer under the formation of subnanometer-sized γ -Al 2 O 3 (111)-type nuclei. The band structure is monitored with angle-resolved photoelectron spectroscopy. Increasing film thickness results in a slight decrease of the work function, but does not lead to significant changes of the electronic band structure. The presented multistep procedure opens a route for the synthesis of thin film structures in general and in particular provides fundamental insight in the surface structure of spinel-based transition Al 2 O 3 .

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Self-assembling of atomic vacancies at an oxide/intermetallic alloy interface

Cited by 106 publications

References 20 publications

pH Effect on Sulfur-Induced Passivity Degradation of Alloy 800 in Simulated Crevice Chemistries

pH Effect on Sulfur-Induced Passivity Degradation of Alloy 800 in Simulated Crevice Chemistries

Compositional tuning of ultrathin surface oxides on metal and alloy substrates using photons: Dynamic simulations and experiments

From two- to three-dimensional alumina: Interface templated films and formation of γ−Al2O3 (111) nuclei

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