Optical absorption of polydisperse TiO2: Effect of surface doping by transition metal cations

Kernazhitsky, L.; Shymanovska, V.; Gavrilko, T.; Naumov, V. V.; Kshnyakin, V.

doi:10.3116/16091833/14/1/15/2013

Cited by 12 publications

(6 citation statements)

References 31 publications

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“…6 shows the curve (αhv) 1/2 versus hv for cobalt doped TiO 2 . By extrapolating the linear part of this curve we have obtained the indirect bandgap 1.64 eV, which is smaller than 3.08 reported for pure TiO 2 [58]. The cobalt doped (colored) sample also absorbs light in the visible region around 1.64 eV (red light) in agreement with the sample being green.…”

Section: Optical Bandgapmentioning

confidence: 56%

Structural determination of Co/TiO2 nanocomposite: XRD technique and simulation analysis

Mostaghni

Abed

2016

Materials Science-Poland

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Synthesis and complex theoretical and experimental studies of Co/TiO 2 anatase have been reported. The preparation of Co/TiO 2 was carried out by sol-gel method. Distribution of cations among the two tetrahedral and octahedral sites was estimated by analyzing the powder X-ray diffraction patterns by employing Rietveld refinement technique, and the results revealed the existence of tetragonal structure. Band structure and density of states calculations were performed using the first-principles methods. The structural and electronic properties of Co/TiO 2 were calculated in the general gradient approximation (GGA). An additional comparison with pure TiO 2 anatase allowed us to clarify cobalt doping effect on the electronic structure and the band gap. The band gap of Co/TiO 2 was decreased by broadening the valence band as a result of the overlap among Co 3d, Ti 3d, and O 2p states, which made it respond better to visible and solar light.

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Section: Optical Bandgapmentioning

confidence: 56%

Structural determination of Co/TiO2 nanocomposite: XRD technique and simulation analysis

Mostaghni

Abed

2016

Materials Science-Poland

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“…In our case, apparent shifts of absorption edge for doped TiO 2 are suggested to be mostly a result of different dispersion of TiO 2 samples. 14 In the case of rutile, as the dominant phase in our samples, the fundamental absorption edge is formed by direct-forbidden and indirect-allowed transitions [40][41][42]. The direct-forbidden transition is considered to be rather week compared with indirect-allowed transition.…”

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confidence: 99%

Influence of the Dopant Concentration on the Photocatalytic Activity: Al-Doped TiO₂

et al. 2015

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The set of Al-doped titania x-Al-TiO 2 (x = 0.0, 0.1, 0.3, 0.5, 0.7, 0.9, 1.1 wt% Al) has been synthetized by sol-gel method and tested in the reaction of photocatalytic degradation of phenol in aqueous suspension. XRD and Raman studies show that TiO 2 samples have mixedphase rutile-anatase crystalline structure with linear increase of anatase fraction from 0.0 wt% for 0.0-Al-TiO 2 up to 18 wt% for 1.1-Al-TiO 2 . The decrease of the particle size from ∼ 800 nm to 50 nm and the increase of specific surface area from 1.7 m 2 /g up to 28 m 2 /g with increased content of Al have been observed. The data of XRD, XPS, Raman spectroscopy and EDS

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“…(3) There are plenty of reports in the literature related to TiO 2 thin films e.g., Refs. , however, in this work we aim at optical absorption spectra simulated by a simple model of absorption coefficient α as a function of photon energy E in order to find the grain size and grain size distribution. After some modifications on this model (to be suitable for the degeneracy of energy levels), transition energies and oscillator strengths for each transition were determined.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Strain and Grain Size on Phonon and Electron Confinements in TiO₂ Thin Films

Nassar

Yükselici

2018

Physica Status Solidi (b)

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Titanium dioxide (TiO 2 ) powder in anatase phase is thermally evaporated by physical vapor deposition (PVD) on glass substrates. Different-thickness TiO 2 thin films are deposited on glass slides. The samples are then optically and structurally investigated using optical absorption (ABS) and Raman scattering (RS). Optical absorption spectroscopy shows that Urbach energy (E U ) related to the width of the long-wavelength tail decreased from 212 to 176 meV as the film thickness increased from 143 to 221 nm, respectively. The grain size, which depends on thickness of the film, and the grain size distribution are evaluated by fitting the absorption coefficient α experimental data to a model of α as a function of energy E. Absorption edge energy (E R ) is also calculated, it decreases by 165 meV as the film thickness increases from 143 to 221 nm. The energies of band gap transitions are also determined from the observed data of absorption. There are two types of transitions, i.e., direct and indirect transitions, in the TiO 2 compound. The phonon confinement model is used to interpret the size effect in Raman scattering. Relative to the Raman active E g mode of bulk TiO 2 crystal, a size-dependent blue shift is noticed in the Raman bands for the first and second E g modes (E 1 ð Þ g : %144 cm À1 and E 2 ð Þ g : 197 cm À1 , respectively). In this study, the results of Raman scattering and optical absorption are combined together in order to investigate the grain size effect, structural disorder, and thickness-dependent strain. In ABS spectroscopy, it is noticed that (at certain wavelength) the intensity of the transmitted light for the thinner sample is higher than that for the thicker one, which is compatible with the relation I ¼ I 0 e Àαt , where α is the absorption coefficient and t is the thickness.

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Optical absorption of polydisperse TiO2: Effect of surface doping by transition metal cations

Cited by 12 publications

References 31 publications

Structural determination of Co/TiO2 nanocomposite: XRD technique and simulation analysis

Structural determination of Co/TiO2 nanocomposite: XRD technique and simulation analysis

Influence of the Dopant Concentration on the Photocatalytic Activity: Al-Doped TiO₂

The Effect of Strain and Grain Size on Phonon and Electron Confinements in TiO₂ Thin Films

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Optical absorption of polydisperse TiO2: Effect of surface doping by transition metal cations

Cited by 12 publications

References 31 publications

Structural determination of Co/TiO2 nanocomposite: XRD technique and simulation analysis

Structural determination of Co/TiO2 nanocomposite: XRD technique and simulation analysis

Influence of the Dopant Concentration on the Photocatalytic Activity: Al-Doped TiO2

The Effect of Strain and Grain Size on Phonon and Electron Confinements in TiO2 Thin Films

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Influence of the Dopant Concentration on the Photocatalytic Activity: Al-Doped TiO₂

The Effect of Strain and Grain Size on Phonon and Electron Confinements in TiO₂ Thin Films