On the optical indices of oxide films as a function of their crystallization: Application to anodic TiO2 (anatase)

Blondeau, G.; Froelicher, M.; Froment, M.; Goff, A. Hugot‐Le

doi:10.1016/0040-6090(77)90411-4

Cited by 52 publications

(42 citation statements)

References 14 publications

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“…By contrast the rutile phase formed on the Ti6Al4V alloy is only present in the 25 V anodised layer whilst the anatase phase is present for all anodising voltages. However this issue has been controversial due to thermochemical data that show that anatase is metastable with respect to rutile and some argue that this conversion from rutile to anatase is not definitive [15,17,39]. Furthermore, Diamanti and Pedeferri [40] reported that in their XRD analysis two opposite trends were observed: oxide conversion to anatase which was promoted either by an increase in current density or by a decrease in sulphuric acid concentration.…”

Section: Resultsmentioning

confidence: 91%

“…This indicates that rutile is converted to the anatase. Similarly, Arsov [15] and Blondeau et al [17] argue that the rutile phase is converted to the anatase phase in the anodised oxide film as the voltage is increased. By contrast the rutile phase formed on the Ti6Al4V alloy is only present in the 25 V anodised layer whilst the anatase phase is present for all anodising voltages.…”

Section: Resultsmentioning

confidence: 96%

“…The specimens were anodised at three different voltages, namely 25 V, 50 V and 75 V for 0.5 h [10,[15][16][17]. The thickness of the anodised layer varied linearly with the voltage at a rate of ≈2 nm/V.…”

Section: Methodsmentioning

confidence: 99%

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Adhesion of sol–gel derived hydroxyapatite nanocoatings on anodised pure titanium and titanium (Ti6Al4V) alloy substrates

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Heness

et al. 2011

Surface and Coatings Technology

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Section: Resultsmentioning

confidence: 91%

Section: Resultsmentioning

confidence: 96%

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Adhesion of sol–gel derived hydroxyapatite nanocoatings on anodised pure titanium and titanium (Ti6Al4V) alloy substrates

Roest

Latella

Heness

et al. 2011

Surface and Coatings Technology

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“…On certain sets of equations we have also solved the system for es = ~3' --i~z" the optical constants of the alloy; the results are less accurate because the set of experimental results is small (6). From the dielectric constants of the substrate obtained, and comparing to results obtained for pure Ti (13,14,6) it was not possible to see the copper influence.…”

Section: Resultsmentioning

confidence: 97%

Influence of Copper Addition on Optical Properties of TiO2

Blondeau¹,

Froelicher²,

Froment³

et al. 1979

J. Electrochem. Soc.

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Cu-doped TiO~ could be considered as a better absorber of sunlight for solar energy conversion. The Cu-doped TiO2 has been prepared by anodic oxidation of a Ti-2.5% Cu alloy. The structural properties of these anodic oxides are examined by electron microdiffraction, XPS, and nuclear microanalysis. The optical properties of both the Ti-Cu alloy and the anodic films have been determined as functions of the thickness of the oxides. It is concluded that Cu doping o~ TiO2 creates an extra state in the forbidden gap of TiO2 which gives two extra peaks in the absorption spectrum of the oxide. But for solar energy applications, the preparation of the doped oxide by anodic oxidation is not suitable because one does not control the level of impurity.Titanium dioxide electrodes created a great interest in the field of semiconductor-electrolyte interfaces when it was shown by Fijishima and Honda (1). that water photoelectrolysis was possible without degradation or decomposition of the semiconductor electrode. For solar applications, however, TiO2 is not suitable because the bandgap of this oxide is 3 eV (410 nm) too far away in the u.v. region to significantly absorb the solar energy. A great amount of work has been done to find the right semiconductor electrode with a bandgap around 2 eV (620 nm) and stability comparable to the TiO2 electrode; two review articles (2, 3) summarize these works. Among the numerous materials or combinations of materials which have been tested to do this water photoe]ectrolysis, TiO2 remains high in the list since it is the most stable material for a long period of time. So the problem is to decrease the TiO~ bandgap or increase the optical absorption in the visible region by increasing the number of defects (holes, vacancies, etc.). Both approaches have been tested on specific systems; Ghosh and Maruska (4) have reported water photoelectrolysis using visible light on a Cr-doped TiO2 electrode, Augustinski et al. (5) have also reported results for TiO~ doped with 6% A120~.Keeping in mind the possible applications of this study we have chosen Cu to fill the bandgap of TiO2. The preparation of Cu-doped TiO2 was made by anodic oxidation of a Ti-Cu alloy which is commercially available and has good mechanical properties. Our purpose is also to show the importance of the knowledge of the optical indexes of both the substrate and the semiconductor film to determine the bandgap shift and the absorption variations due to the incorporation of copper.

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“…Actually, z is about 3.4 for relatively thin galvanostatically grown films due to their rather high non-stoichiometry (TiO 1.7 ) according to Auger depth profiles of these films. Literature values of the q for the anodic oxide films on titanium vary in the range from 3.2 to 3.9 g cm À3 [10,[22][23][24][25]. Taking q = 3.2-3.9 g cm À3 , r s = 1 for a mirror-like finishing of the electrode surface, z = 3.4 and g f = 1, we can obtain d = 68-83 nm at the passed charge Q = 0.11 C cm À2 .…”

Section: Specular Reflectance and Auger Spectroscopy Studiesmentioning

confidence: 99%