Effect of anodizing voltage and pore widening time on the effective refractive index of anodic titanium oxide

Sapoletova, N. A.; Kushnir, Sergey E.; Napolskii, K. S.

doi:10.17586/2220-8054-2019-10-2-154-157

Cited by 5 publications

(2 citation statements)

References 21 publications

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“…The obtained results evidently show that n eff of ATO films obtained at constant voltages decreases slightly (<10%) even after 6 h of storage in the anodizing electrolyte under open-circuit conditions. Similar behaviour of n eff (t) was shown earlier for ethylene glycol based electrolyte without ammonium acetate [18] and with sodium acetate [43]. The calculated values of n eff (1.58-1.77) for ATO films obtained at constant voltages are substantially higher than ones for ATO PhCs (1.19-1.53).…”

Section: The Etching Of Ato Nanotubes Under Open Circuit Conditionssupporting

confidence: 85%

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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Section: The Etching Of Ato Nanotubes Under Open Circuit Conditionssupporting

confidence: 85%

Polarization-enhanced cell walls etching of anodic titanium oxide

Sapoletova¹,

Kushnir²,

Napolskii³

2021

Nanotechnology

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“…Despite the fluctuations, there is a general tendency of growth of n as V increases.The solution without NaF increases steadily in the voltage range observed. The growth of the refractive index of TiO2 at 700 nm as anodization potential is applied was also observed bySapoletova et al (2019) in a different solution in the range of 35 V to 50 V.…”

mentioning

confidence: 82%

Effect of fluoride on the thickness, surface roughness and corrosion resistance of titanium anodic oxide films formed in a phosphate buffer solution at different applied potentials

Domingues

Oliveira

Ferreira

et al. 2020

RSD

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The anodizing process and anions type present in the electrolyte during anodic oxidation are important parameters to improve oxide biocompatibility. From these parameters, it is possible to control the thickness and surface roughness of the oxide film. This control is of major importance, once blood clots can be avoided when the oxide film on the metal substrate has a small surface roughness (Ra ≤ 50 nm). In this paper, the thickness, surface roughness, and corrosion resistance of the anodized titanium film were studied in a phosphate buffer solution containing fluoride anions (0.6 w.t % NaF), at 20 V, 40 V, 60 V, and 80 V, using atomic force microscopy (AFM), spectroscopic ellipsometry (SE), and electrochemical impedance spectroscopy (EIS) techniques. It was observed that thickness and roughness tend to increase as the applied potential rises. For oxides grown in the solution without NaF, the growth rate is roughly 1.3 ± 0.2 nm/V. Surface roughness generally presents the same behaviour. Moreover, EIS and SE thickness measurements agree at 20 V and 60 V but disagree at 80 V. This may be associated with a possible dielectric breakdown at 80 V. The oxide film formed at 60 V showed the best corrosion resistance in relation to the other studied potentials. Globular structures were also observed using AFM on surfaces at 40 V, 60 V, and 80 V, which suggests oxide film nucleation. Oxide films formed in solution with NaF presented lower thickness, excellent corrosion resistance, and low surface roughness (Ra ≤ 50 nm).

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