Micro-EIS of anodic thin oxide films on titanium for capacitor applications

Schneider, Michael; Schroth, S.; Schilm, Jochen; Michaelis, Alexander

doi:10.1016/j.electacta.2008.11.003

Cited by 55 publications

(47 citation statements)

References 38 publications

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“…Such a behav iour has been frequently observed for semiconducting passive films grown on a number of valve metal ( [3] and refs. therein) and very recently it has been observed also on amorphous TiO 2 film grown on dif ferent single grains of pure (99.9%) titanium [29]. The frequency dependence of the capacitance is reflected in Mott-Schottky plots usually showing both donor density and flat band potential values frequency dependent [4,[29][30][31][32].…”

Section: Electrochemical Impedance Spectroscopy (Eis)mentioning

confidence: 91%

“…therein) and very recently it has been observed also on amorphous TiO 2 film grown on dif ferent single grains of pure (99.9%) titanium [29]. The frequency dependence of the capacitance is reflected in Mott-Schottky plots usually showing both donor density and flat band potential values frequency dependent [4,[29][30][31][32]. When this occurs for crystalline semiconductor/electrolyte junctions several physical explanations have been suggested in the literature as possible source of this dependence [33][34][35][36] [5,[16][17][18]37] that frequency dependent differential admittance val ues are theoretically expected for amorphous semi conductor passive film/electrolyte junction in agree ment with the theory of amorphous semiconductor Schottky barriers.…”

Section: Electrochemical Impedance Spectroscopy (Eis)mentioning

confidence: 95%

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A critical assessment of the Mott-Schottky analysis for the characterisation of passive film-electrolyte junctions

et al. 2010

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Abstract-The widespread use of the Mott-Schottky plots to characterize the energetics of passive film/electrolyte junction is critically reviewed in order to point out the limitation of such approach in describ ing the electronic properties of passive film as well in deriving the correct location of the characteristic energy levels of the junction. The frequency dependency of M-S plots frequently observed in the experimental data gathered in a sufficiently large range of frequency is extensively discussed for a relatively thick (160 nm) ther mally aged amorphous niobia (α Nb 2 O 5 ) film immersed in electrolytic solution. The relatively simple equiv alent electrical circuit describing an ideally blocking behaviour of the junction allows a direct comparison of the experimental data analysis based on the use of Mott-Schottky or amorphous semiconductor Schottky barrier interpretative models. Moreover the theoretical simulations of the M-S plots based on the theory of crystalline semiconductor suggest an electronic structure of the investigated passive film containing a distri bution of localized electronic states deep lying in energy in agreement with the model of amorphous semi conductor Schottky barrier.

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Section: Electrochemical Impedance Spectroscopy (Eis)mentioning

confidence: 91%

Section: Electrochemical Impedance Spectroscopy (Eis)mentioning

confidence: 95%

A critical assessment of the Mott-Schottky analysis for the characterisation of passive film-electrolyte junctions

et al. 2010

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“…This result means that the dominant defects in all the passive films are oxygen vacancies and/or cation interstitials [46]. Such two linear regions at low and high potentials were reported to be attributed to the semiconducting behavior and dielectric character of the passive film, respectively [47]. In the present study, the linear region at low potential was chosen to calculate the semiconductor property parameters of the passive films formed on the tested samples.…”

Section: Mott-schottky Analysismentioning

confidence: 99%

Nanocrystalline β-Ta Coating Enhances the Longevity and Bioactivity of Medical Titanium Alloys

Liu

Jiang

2016

Metals

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A β-Ta nanocrystalline coating was engineered onto a Ti-6Al-4V substrate using a double cathode glow discharge technique to improve the corrosion resistance and bioactivity of this biomedical alloy. The new coating has a thickness of~40 µm and exhibits a compact and homogeneous structure composed of equiaxed β-Ta grains with an average grain size of~22 nm, which is well adhered on the substrate. Nanoindentation and scratch tests indicated that the β-Ta coating exhibited high hardness combined with good resistance to contact damage. The electrochemical behavior of the new coating was systematically investigated in Hank's physiological solution at 37 • C. The results showed that the β-Ta coating exhibited a superior corrosion resistance as compared to uncoated Ti-6Al-4V and commercially pure tantalum, which was attributed to a stable passive film formed on the β-Ta coating. The in vitro bioactivity was studied by evaluating the apatite-forming capability of the coating after seven days of immersion in Hank's physiological solution. The β-Ta coating showed a higher apatite-forming ability than both uncoated Ti-6Al-4V and commercially pure Ta, suggesting that the β-Ta coating has the potential to enhance functionality and increase longevity of orthopaedic implants.

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“…The capacitance data were used to obtain a qualitative estimation of the dielectric permittivities of the anodic films after anodizing in the two acids. According to the calculation by T = εε 0 /C, 4 where T is the anodic film thickness (nm), ε is the dielectric permittivity of TiO 2 formed in each acid, ε 0 is the dielectric permittivity of free space (8.85 × 10 −12 F m −1 ) and C is the oxide capacitance (F cm −2 ) and the real film thickness measured by TEM, the dielectric permittivities of the anodic films formed after anodizing at 50 V in the sulfuric acid and phosphoric acid are calculated to be ∼77.6 and ∼62.4 respectively. The dielectric permittivity estimated by EIS Figure 8.…”

Section: X-ray Diffraction and X-ray Photoelectron Spectroscopy-diffmentioning

confidence: 99%

“…2 Further, the thickness of the anodic oxide layer has been shown to be a linear function of the applied voltage. [2][3][4][5] The anodic oxide film on titanium is basically amorphous in crystal structure and morphologically homogeneous. 6 Moreover, such an oxide layer provides excellent resistance to corrosion as indicated electrochemically by a low level of electronic conductivity, 7 thermodynamically great stability 8 and low ion-formation tendency in aqueous environments.…”

mentioning

confidence: 99%

Anodic Film Growth of Titanium Oxide Using the 3-Electrode Electrochemical Technique: Effects of Oxygen Evolution and Morphological Characterizations

Liu

Zhong

Walton

et al. 2015

J. Electrochem. Soc.

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In the present study, potentiodynamic polarization scans followed by potentiostat anodizing tests have been employed to generate the anodic oxide films on commercially pure Ti in 1 M sulfuric acid and 1 M phosphoric acid. The highly stable single-barrier anodic films with a growth ratio of ∼1.5 nm V −1 (sulfuric acid) or ∼1.7 nm V −1 (phosphoric acid) were generated at the anodic voltages from 10 V to 60 V. During the potentiostatic anodizing, the anodic film was formed after the growth of the passive oxide film in the potentiodynamic polarization stage. Oxygen evolution proceeded within both the polarization and the anodizing stages, resulting in the suppression of the current efficiency for the growth of anodic films. The oxygen bubbles were induced by the amorphous-to-crystalline transition within the anodic film, leading to the formation of blister textures. Significant rupture of the anodic film was found that started at 20 V of the anodizing processes in the sulfuric acid; conversely, the significant rupture was started at 50 V in the phosphoric acid. The XRD results indicated that the degree of amorphous-to-crystalline transition in the anodic film formed in the phosphoric acid was less than the film formed in the sulfuric acid. The phosphate titanium oxide layers detected by XPS in the phosphoric acid indicated that more degrees of the amorphous-to-crystalline transition might be inhibited compared with the sulfated titanium oxides found in the sulfuric acid. Titanium can be anodized in acidic and basic solutions under potentiostatic or galvanostatic conditions. In view of the variation of titanium anodizing conditions, it is possible to tailor the anodic film thickness formed on the surface of titanium.1 The coloration of the oxide film produced through anodic oxidation is indicative of the thickness. This relation between color and thickness of the oxide is dependent on the anodizing condition and the nature of the electrolyte. Further, the thickness of the anodic oxide layer has been shown to be a linear function of the applied voltage.2-5 The anodic oxide film on titanium is basically amorphous in crystal structure and morphologically homogeneous.6 Moreover, such an oxide layer provides excellent resistance to corrosion as indicated electrochemically by a low level of electronic conductivity, 7 thermodynamically great stability 8 and low ion-formation tendency in aqueous environments. 9 The growth of the oxide thickness results in systemic changes of the surface topography, particularly in the surface pore configuration, 10 whereas electrolyte derived anion incorporation into oxide films will modify the chemical composition as well as the crystal structure. [11][12][13] It is generally known that titanium behaves as a typical valve metal for which oxide growth involves field-assisted migration of ions through the films and for the thickness to follow Faraday's law. [14][15][16] Further, the growth constant values of the anodic film are variable according to many academics. 17,18 It is reported that a...

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Micro-EIS of anodic thin oxide films on titanium for capacitor applications

Cited by 55 publications

References 38 publications

A critical assessment of the Mott-Schottky analysis for the characterisation of passive film-electrolyte junctions

A critical assessment of the Mott-Schottky analysis for the characterisation of passive film-electrolyte junctions

Nanocrystalline β-Ta Coating Enhances the Longevity and Bioactivity of Medical Titanium Alloys

Anodic Film Growth of Titanium Oxide Using the 3-Electrode Electrochemical Technique: Effects of Oxygen Evolution and Morphological Characterizations

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