Analytical 3D migration model of steady-state metal anodizing: the velocity fields and trajectories of inert tracers, metal and oxygen ions

Mirzoev, R. A.; Давыдов, А. Д.; Zarubenko, E.S.; Vystupov, S.I.; Panteleev, E.S.

doi:10.1016/j.electacta.2016.09.115

Cited by 13 publications

(4 citation statements)

References 33 publications

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“…Then, their concentration decreases and becomes almost zero at the aluminum oxide/metal interface as well as at cell-wall boundaries. The distribution of incorporated anions in pore walls and the barrier layer is in agreement with theoretical models calculated by Mirzoev et al [86,87]. A special case of anodizing in chromic acid is characterized by the absence of incorporated anions (Figure 5d).…”

Section: Mechanism Of Anions Incorporation: Duplex and Triplex Structuresupporting

confidence: 89%

Incorporation of Ions into Nanostructured Anodic Oxides—Mechanism and Functionalities

2021

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Anodic oxidation of metals leads to the formation of ordered nanoporous or nanotubular oxide layers that contribute to numerous existing and emerging applications. However, there are still numerous fundamental aspects of anodizing that have to be well understood and require deeper understanding. Anodization of metals is accompanied by the inevitable phenomenon of anion incorporation, which is discussed in detail in this review. Additionally, the influence of anion incorporation into anodic alumina and its impact on various properties is elaborated. The literature reports on the impact of the incorporated electrolyte anions on photoluminescence, galvanoluminescence and refractive index of anodic alumina are analyzed. Additionally, the influence of the type and amount of the incorporated anions on the chemical properties of anodic alumina, based on the literature data, was also shown to be important. The role of fluoride anions in d-electronic metal anodizing is shown to be important in the formation of nanostructured morphology. Additionally, the impact of incorporated anionic species, such as ruthenites, and their influence on anodic oxides formation, such as titania, reveals how the phenomenon of anion incorporation can be beneficial.

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Section: Mechanism Of Anions Incorporation: Duplex and Triplex Structuresupporting

confidence: 89%

Incorporation of Ions into Nanostructured Anodic Oxides—Mechanism and Functionalities

2021

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“…SEM images of ATO PhCs x35 etched at U=0 and 40 V are shown in figure 8. Pore diameter and porosity of ATO PhC etched at U=40 V are clearly higher than the Existent theories of anodizing of valve metals deal with processes that occurred at the pore bottom: field-assisted dissolution [44] and field-assisted ejection theories [45], plastic flow model [46], and migration model [47]. The etching process of ATO cell walls is associated solely with chemical reactions between the anodic oxide and fluoridecontaining electrolyte species [26,[48][49][50][51][52][53].…”

Section: The Etching Of Ato Phcs Under Anodic Polarizationmentioning

confidence: 89%

Polarization-enhanced cell walls etching of anodic titanium oxide

Sapoletova¹,

Kushnir²,

Napolskii³

2021

Nanotechnology

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Anodic titanium oxide (ATO) photonic crystals (PhCs) are promising for photonics, photocatalysis, and solar cells. A refractive index modulation in ATO PhCs is caused by the modulation of porosity and, thus, the pore diameter should be controlled precisely. The ATO cell walls etching in electrolyte solution during anodizing increases the porosity of the PhC structure and shifts the photonic band gap (PBG) position to shorter wavelengths. Until now, the ATO cell walls etching in organic based electrolytes has been associated solely with the chemical dissolution of ATO in fluoride-containing solutions. Here, a significant enhancement of cell walls etching is observed when electric current flows under anodic polarization. This effect leads to the blue shift of the PBG position with the number of periods of ATO PhC structure. Therefore, it is essential for the synthesis of ATO PhCs with a precise PBG position.

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“…However, a vast amount of experimental data contradicting FAD model has been accumulated to date. In particular, the FAD model incorrectly predicts the experimental growth rate of AAO porous films, 10 it is also incapable of describing the non-monotonous distribution of impurities inside cell walls 11 and the existence of narrow windows of anodizing conditions leading to the self-ordering of pores. 12,13 These phenomena have prompted the development of alternative models, one of which considers the presence of viscous flows of anodic oxide at the pore bases.…”

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confidence: 99%

“…14 Using these considerations, the authors have explained the experimentally observed pathways of W atoms embedded as tracers into the metal layer being anodized. 14,15 Recently, the analytical model has been suggested 10,16 allowing to calculate the pathways of neutral and charged tracers by means of equations describing the ions migration inside the barrier layer of AAO films. Without recourse to the viscous flow model, the authors of the research succeeded to explain a number of experimental observations, including the distribution of W tracers 14,15 and the presence of pure and electrolyte-contaminated layers in the structure of AAO cell walls.…”

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confidence: 99%

Probing Barrier Oxide Layer of Porous Anodic Alumina by In Situ Electrochemical Impedance Spectroscopy

Leontiev

Napolskii

2021

J. Electrochem. Soc.

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Electrochemical impedance spectroscopy (EIS) is a unique tool for both ex situ and in situ studies of the barrier layer thickness of anodic aluminium oxide (AAO). Here EIS is applied to study porous AAO formed by anodizing of high-purity Al foils in 0.3 M sulphuric acid and 0.3 M oxalic acid electrolytes. It is shown that in the high-frequency range, in situ EIS spectra coincide with the ex situ ones. Thus, the thickness of the barrier layer at the pore bases does not change after the end of the anodic polarization. The barrier layer thickness (h) is governed by the anodizing potential (U) according to the equation h = 1.03(2) nm·V−1·U + 2.2(3) nm. Features of the current transients observed during potentiostatic anodizing are discussed. It has been proved that a local maximum of current at the initial stage of anodizing corresponds to the maximum of the aluminium electroactive surface area arising due to the rearrangement of pores.

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Analytical 3D migration model of steady-state metal anodizing: the velocity fields and trajectories of inert tracers, metal and oxygen ions

Cited by 13 publications

References 33 publications

Incorporation of Ions into Nanostructured Anodic Oxides—Mechanism and Functionalities

Incorporation of Ions into Nanostructured Anodic Oxides—Mechanism and Functionalities

Polarization-enhanced cell walls etching of anodic titanium oxide

Probing Barrier Oxide Layer of Porous Anodic Alumina by In Situ Electrochemical Impedance Spectroscopy

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