A theory of avalanche breakdown during anodic oxidation

Albella, J.M.; Montero, I.; Martı́nez-Duart, J.M.

doi:10.1016/0013-4686(87)85032-6

Cited by 270 publications

(209 citation statements)

References 17 publications

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“…Mazzarolo et al 26 indicated that structural transformation and oxygen evolution are dependent on the incorporation of fluoride ions within the film. Albella et al 32 demonstrated that the primary electronic current is attributed to the electrons released by the incorporation of electrolyte species into the oxide. In summary, anion contaminated layer always exists near the electrolyte/oxide interface as long as the electric field is applied.…”

Section: Resultsmentioning

confidence: 99%

Formation Mechanism of Gaps and Ribs Around Anodic TiO₂Nanotubes and Method to Avoid Formation of Ribs

Chong

Gao

et al. 2015

J. Electrochem. Soc.

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Anodic TiO 2 nanotubes (ATNTs) have been studied extensively for many years. However, their mysterious formation mechanism still remains unclear. The formation of gaps and ribs around the nanotubes has not been elucidated. Here, various surface and cross-section morphologies of ATNTs obtained under different anodizing conditions and their evolution process have been investigated in detail. Based on many experimental facts, new explanations for the gaps and ribs are presented. An entire surface layer covered on the nanotubes plays a primary role on the formation of gaps and ribs. The gaps result from the radial distribution of the electric field at the pore bottom. No newly-formed oxide will exist along the gap direction, because the electric filed along the gap is the minimum. The ribs result from the electrolyte entering into the wider gaps among the ATNTs due to the rupture of the entire surface layer. The rings or ribs on the outer wall of ATNTs are formed at the electrolyte/Ti interface due to the discontinuous existence of a small amount of electrolyte within the gap base. The present viewpoint was demonstrated by an original micro-dam, which can block the electrolyte entering into the gaps and avoid the formation of ribs.

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Section: Resultsmentioning

confidence: 99%

Formation Mechanism of Gaps and Ribs Around Anodic TiO₂Nanotubes and Method to Avoid Formation of Ribs

Chong

Gao

et al. 2015

J. Electrochem. Soc.

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“…In the anodization processes, it has been known that the J is made up of ionic current density (J i ) and electronic current density (J e ), and the J i can be further divided into two parts: oxidation current density (J o ) and incorporation current density (J c ). The J o represents the inwardly migrating O 2− anions during the anodization and has a direct relationship with the formation of AAO, while the J c can be ascribed to the migration of contaminated species (e.g., different types of acid radical anions) which makes no direct contribution to the formation of AAO [58,59]. The relationship among these current densities was shown and illustrated in Fig.…”

Section: The Maximum Anodization Voltage and The Breakdown Processmentioning

confidence: 98%

Mechanisms of Nanoporous Alumina Formation and Self-organized Growth

Ling

2015

Nanoporous Alumina

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The synthesis of nanoporous alumina based on anodization process is a field of active research. In this chapter, some fundamental scientific topics toward formation mechanisms of nanoporous alumina will be discussed in detail.(1) The intrinsic mechanisms of mild and hard anodization processes: the definition of mild anodization (MA) and hard anodization (HA); the critical condition between MA and HA processes. (2) The origins of self-ordering phenomenon: the structure models of nanoporous alumina; the influence of electrical field and internal stress. (3) The growth models of nanoporous alumina: the classical growth models of nanoporous alumina; the advantages and disadvantages of present models; the physical and chemical processes during aluminum anodization. (4) The intrinsic relationship between anodization conditions and anodization processes: the influence of anodization voltage and current density; the influence of electrolyte system; the influence of other anodization conditions. (5) Controllable fabrication of nanoporous alumina: the relationship between anodization conditions and structural parameters (e.g., interpore distance, pore size); fabrication of regular nanoporous alumina (i.e., with highly ordered pores); fabrication of nanoporous alumina with complex pore structure. In addition to nanoporous alumina, the findings and conclusions in this chapter may also be applied in other valve metal anodization processes (e.g., Ti, Zr, W anodization).

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“…This large current promotes the electrical discharge. In addition to this model, Albella et al [11] proposed that the primary source of electrons are the electrolyte species incorporated into the oxide. These species behave as impurities centers and can be ionized by the high electric field releasing electrons that can be accelerated producing an avalanche by impact ionization mechanism.…”

Section: Resultsmentioning

confidence: 99%

“…The anodic oxides obtained from valve metals have been investigated since 50's, at the time, for development of new materials for capacitors [6][7][8]. Several models have been proposed in the literature in order to explain the electrolytic breakdown observed during the growth of the anodic oxides from valve metals, such as electron avalanche [9][10][11], mechanical breakdown [12,13] and pit formation [13][14][15][16]. However, due its complexity, there is not a generally accept complete mechanistic overview of the breakdown phenomenon in valve metal oxides.…”

Section: Introductionmentioning

confidence: 99%

Characterization of electrical discharges during spark anodization of zirconium in different electrolytes

Santos

Lemos

Gonçalves

et al. 2014

Electrochimica Acta

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A theory of avalanche breakdown during anodic oxidation

Cited by 270 publications

References 17 publications

Formation Mechanism of Gaps and Ribs Around Anodic TiO₂Nanotubes and Method to Avoid Formation of Ribs

Formation Mechanism of Gaps and Ribs Around Anodic TiO₂Nanotubes and Method to Avoid Formation of Ribs

Mechanisms of Nanoporous Alumina Formation and Self-organized Growth

Characterization of electrical discharges during spark anodization of zirconium in different electrolytes

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A theory of avalanche breakdown during anodic oxidation

Cited by 270 publications

References 17 publications

Formation Mechanism of Gaps and Ribs Around Anodic TiO2Nanotubes and Method to Avoid Formation of Ribs

Formation Mechanism of Gaps and Ribs Around Anodic TiO2Nanotubes and Method to Avoid Formation of Ribs

Mechanisms of Nanoporous Alumina Formation and Self-organized Growth

Characterization of electrical discharges during spark anodization of zirconium in different electrolytes

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Product

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Formation Mechanism of Gaps and Ribs Around Anodic TiO₂Nanotubes and Method to Avoid Formation of Ribs

Formation Mechanism of Gaps and Ribs Around Anodic TiO₂Nanotubes and Method to Avoid Formation of Ribs