Optical Studies of Nanophase Titania

Gonzalez, Reinaldo; Zallen, Richard

doi:10.1007/978-94-015-8832-4_18

Cited by 11 publications

(11 citation statements)

References 14 publications

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“…This is even more so that under our present fluences (see Supplementary Material ) 16 29 , a Fermi liquid probably forms in the CB. The scenario in which electron-phonon coupling is operative would also be an ultrafast process given the period of the E u antiphase breathing mode of the oxygen atoms (oscillation period of ~40 fs) 5 38 39 . Thus, whichever mechanism is in play (direct trapping or mediated by electron-phonon coupling), electron trapping at defects is ultrafast.…”

mentioning

confidence: 99%

Femtosecond X-ray absorption study of electron localization in photoexcited anatase TiO2

Santomauro

Lübcke

Rittmann

et al. 2015

Sci Rep

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Transition metal oxides are among the most promising solar materials, whose properties rely on the generation, transport and trapping of charge carriers (electrons and holes). Identifying the latter’s dynamics at room temperature requires tools that combine elemental and structural sensitivity, with the atomic scale resolution of time (femtoseconds, fs). Here, we use fs Ti K-edge X-ray absorption spectroscopy (XAS) upon 3.49 eV (355 nm) excitation of aqueous colloidal anatase titanium dioxide nanoparticles to probe the trapping dynamics of photogenerated electrons. We find that their localization at Titanium atoms occurs in <300 fs, forming Ti3+ centres, in or near the unit cell where the electron is created. We conclude that electron localization is due to its trapping at pentacoordinated sites, mostly present in the surface shell region. The present demonstration of fs hard X-ray absorption capabilities opens the way to a detailed description of the charge carrier dynamics in transition metal oxides.

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mentioning

confidence: 99%

Femtosecond X-ray absorption study of electron localization in photoexcited anatase TiO2

Santomauro

Lübcke

Rittmann

et al. 2015

Sci Rep

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“…29,30 For both materials, an amorphous TiO 2 layer with small amounts of crystalline anatase was formed at lower potentials. For the same current density, with increasing formation voltage more and more amorphous TiO 2 transforms into the crystalline anatase structure, i.e., TiO 4 tetrahedrons transform to TiO 6 octahedrons.…”

Section: 28mentioning

confidence: 99%

Preparation of TiO₂ layers on cp‐Ti and Ti6Al4V by thermal and anodic oxidation and by sol‐gel coating techniques and their characterization

Velten

Biehl

Aubertin

et al. 2001

J. Biomed. Mater. Res.

307

215

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The excellent biocompatibility of titanium and its alloys used, for example, for medical devices, is associated with the properties of their surface oxide. For a better understanding of the tissue reaction in contact with the oxide layer, knowledge of the chemical and physical properties of this layer is of increasing interest. In this study, titania films were produced on cp-Ti and Ti6Al4V substrates by thermal oxidation, anodic oxidation, and by the sol-gel process. The thickness and structure of the films produced under different conditions were determined by ellipsometry, infrared spectroscopy, and X-ray diffraction measurements. The corrosion properties of these layers were investigated by current density-potential curves under physiological conditions. The oxide layers produced on cp-Ti and Ti6Al4V by thermal oxidation consist of TiO(2) in the rutile structure. For the anodized samples the structure of TiO(2) is a mixture of amorphous phase and anatase. The structure of the coatings produced by the sol-gel process for a constant annealing time depends on the annealing temperature, and with increasing temperature successively amorphous, anatase, and rutile structure is observed. Compared to the uncoated, polished substrate with a natural oxide layer, the corrosion resistance of cp-Ti and Ti6Al4V is increased for the samples with an oxide layer thickness of about 100 nm, independent of the oxidation procedure.

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“…Among these methods the infrared (IR) laser synthesis from gas or liquid precursors, usually known as cw CO 2 laserinduced pyrolysis, offers the advantage of a clean technology, producing a fairly uniform and controllable particle size distribution [2]. 3 Author to whom any correspondence should be addressed.…”

Section: Introductionmentioning

confidence: 99%

Infrared study of laser synthesized anatase TiO₂nanopowders

Grujić‐Brojčin¹,

Šćepanović²,

Dohčević‐Mitrović³

et al. 2005

J. Phys. D: Appl. Phys.

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Nanosized titanium dioxide (TiO2) is synthesized by laser-induced pyrolysis using titanium isopropoxide as a liquid precursor. The specific surface area of as-produced nanopowders measured by the Brunauer–Emmett–Teller method (BET) varies from 84 to 110 m2 g−1. X-ray diffraction (XRD) and Raman scattering showed that the TiO2 nanocrystals had an anatase structure. The grain size of the nanoparticles was estimated from scanning electron microscopy, XRD and BET measurements. The reflection spectra of nanocrystalline TiO2 pressed pellets has been measured in the region between 80 and 1500 cm−1 by Fourier transform infrared spectroscopy. To interpret the experimental results, a model based on a generalized Bruggeman effective medium approximation of a dielectric function has been proposed. It is based on the polycrystalline character of TiO2 nanoparticles including island-structure and porosity of the nanopowders, along with the anatase single crystal dielectric functions. Thus, by comparing the results of calculated and experimental infrared (IR) spectra, the values of microscopic parameters of nanocrystalline powders can be deduced.

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Optical Studies of Nanophase Titania

Cited by 11 publications

References 14 publications

Femtosecond X-ray absorption study of electron localization in photoexcited anatase TiO2

Femtosecond X-ray absorption study of electron localization in photoexcited anatase TiO2

Preparation of TiO₂ layers on cp‐Ti and Ti6Al4V by thermal and anodic oxidation and by sol‐gel coating techniques and their characterization

Infrared study of laser synthesized anatase TiO₂nanopowders

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Optical Studies of Nanophase Titania

Cited by 11 publications

References 14 publications

Femtosecond X-ray absorption study of electron localization in photoexcited anatase TiO2

Femtosecond X-ray absorption study of electron localization in photoexcited anatase TiO2

Preparation of TiO2 layers on cp‐Ti and Ti6Al4V by thermal and anodic oxidation and by sol‐gel coating techniques and their characterization

Infrared study of laser synthesized anatase TiO2nanopowders

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Preparation of TiO₂ layers on cp‐Ti and Ti6Al4V by thermal and anodic oxidation and by sol‐gel coating techniques and their characterization

Infrared study of laser synthesized anatase TiO₂nanopowders