Oxygen vacancy related distortions in rutile<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Ti</mml:mi><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>nanoparticles: A combined experimental and theoretical study

Vásquez, G. Cristian; Karazhanov, Smagul; Maestre, David; Cremades, Ana; Piqueras, J.; Foss, Sean Erik

doi:10.1103/physrevb.94.235209

Cited by 47 publications

(21 citation statements)

References 45 publications

(73 reference statements)

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“…Peak A2 can be viewed as a peak A1 replica undergoing an ∼1 eV blue shift under the influence of an O vac . Similar results have been obtained in rutile TiO 2 for which doubly ionized oxygen vacancies introduced blue shift of the Ti 3d-DOS by 1 eV [52]. A similar effect is present in a-TiO 2 at the O K-edge where the asymmetry of the so-called t 2g and e g peaks with a tail on the high-energy side cannot be reproduced in the calculations with a bulk structure [53].…”

Section: B Origin Of Peak A2supporting

confidence: 81%

X-ray absorption linear dichroism at the Ti K edge of anatase TiO2 single crystals

et al. 2019

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Anatase TiO 2 (a-TiO 2 ) exhibits a strong X-ray absorption linear dichroism with the X-ray incidence angle in the pre-edge, the XANES and the EXAFS at the titanium K-edge. In the pre-edge region the behaviour of the A1-A3 and B peaks, originating from the 1s-3d transitions, is due to the strong p-orbital polarization and strong p − d orbital mixing. An unambiguous assignment of the pre-edge peak transitions is made in the monoelectronic approximation with the support of ab initio finite difference method calculations and spherical tensor analysis in quantitative agreement with the experiment. Our results suggest that previous studies relying on octahedral crystal field splitting assignments are not accurate due to the significant p-d orbital hybridization induced by the broken inversion symmetry in a-TiO 2 . It is found that A1 is mostly an on-site 3d-4p hybridized transition, while peaks A3 and B are non-local transitions, with A3 being mostly dipolar and influenced by the 3d-4p intersite hybridization, while B is due to interactions at longer range. Peak A2 which was previously assigned to a transition involving pentacoordinated titanium atoms is shown for the first time to exhibit a quadrupolar angular evolution with incidence angle which implies that its origin is primarily related to a transition to bulk energy levels of a-TiO 2 and not to defects, in agreement with theoretical predictions (Vorwerk et al , Phys. Rev. B, 95, 155121 (2017)). Finally, ab initio calculations show that the occurence of an enhanced absorption at peak A2 in defect rich a-TiO 2 materials is a coincidence of a blue shifted peak A1 due to the chemical shift induced by oxygen vacancies on quadrupolar transitions in the pre-edge. These novel results pave the way to the use of the pre-edge peaks at the Ti K-edge of a-TiO 2 to characterize the electronic structure of related materials and in the field of ultrafast X-ray absorption spectroscopy (XAS) where the linear dichroism can be used to compare the photophysics along different axes.

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Section: B Origin Of Peak A2supporting

confidence: 81%

X-ray absorption linear dichroism at the Ti K edge of anatase TiO2 single crystals

et al. 2019

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“…This is reflected by the vertical lines for rutile, which makes it visually easy to identify our experimental peak locations in relation to the nominal crystal of rutile, which is well known. The agreement is easily accurate to within the small discrepancies concerning these distances that exist in the literature, which vary by about 2 % …”

Section: Resultssupporting

confidence: 52%

Oxygen Vacancy Induced Structural Distortions in Black Titania: A Unique Approach using Soft X‐ray EXAFS at the O–K Edge

Leedahl

Boer

Yuan

et al. 2019

Chemistry A European J

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Unknown changes in the crystalline order of regular TiO2 result in the formation of black titania, which has garnered significant interest as a photocatalytic material due to the accompanying electronic changes. Herein, the nature of the lattice distortion caused by an oxygen vacancy was determined that in turn results in the formation of mid‐band‐gap states found in previous studies of black titania. An innovative technique is introduced using a state‐of‐the‐art silicon drift detector, which can be used in conjunction with extended X‐ray absorption fine structure (EXAFS) to measure bulk interatomic distances. Also discussed is how the energy dispersive nature of such a detector can allow for an unimpeded signal, indefinitely in energy space, thereby sidestepping the hurdles of more conventional EXAFS, which is often impeded by other absorption edges.

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“…All samples exhibit typical diffraction peaks at around 2θ = 27.4°, 36.1°, 39.2°, 41.2°, 44.1°, 54.3°and 56.6 o , corresponding to the (110), (101), (200), (111), (210), (211) and (220) planes of rutile TiO 2 (PDF#21-1276). In addition, with increasing calcination temperature, the diffraction peaks becomes weak and broad gradually, combined with the refined lattice parameter c from 2.959 to 2.958 Å, which may be attributed to the formation of surface oxygen vacancy decreasing the crystallinity of rutile TiO 2 and the distortion of the crystal structure [36]. Raman spectra of the four samples determined the crystalline structure of the samples, as shown in Fig.…”

Section: Resultsmentioning

confidence: 98%

Engineering oxygen vacancy on rutile TiO2 for efficient electron-hole separation and high solar-driven photocatalytic hydrogen evolution

et al. 2018

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Oxygen vacancy related distortions in rutileTiO2nanoparticles: A combined experimental and theoretical study

Cited by 47 publications

References 45 publications

X-ray absorption linear dichroism at the Ti K edge of anatase TiO2 single crystals

X-ray absorption linear dichroism at the Ti K edge of anatase TiO2 single crystals

Oxygen Vacancy Induced Structural Distortions in Black Titania: A Unique Approach using Soft X‐ray EXAFS at the O–K Edge

Engineering oxygen vacancy on rutile TiO2 for efficient electron-hole separation and high solar-driven photocatalytic hydrogen evolution

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