Oxygen-vacancy driven electron localization and itinerancy in rutile-based 
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Lechermann, Frank; Heckel, Wolfgang; Kristanovski, Oleg; Müller, Stefan

doi:10.1103/physrevb.95.195159

Cited by 21 publications

(22 citation statements)

References 85 publications

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“…Figure 1 shows the pDOS patterns of pure and single O-vacancy of anatase and rutile structures, which clearly represented the main contribution of O 2p and Ti 3d orbitals in the valance and conduction bands, respectively. This was in a close agreement with previous results [38][39][40][41], for the defect states of anatase and rutile. The band gap, regardless of defect states, increased by generation of oxygen defect from 3 to 3.4 eV in rutile, and from 3.2 to 3.6 eV in anatase structures, similar to our previous study [43].…”

Section: O-vacancy In the Bulk Structure Of Rutile And Anatasesupporting

confidence: 93%

“…Theory has also shown that O-vacancies cannot diffuse to the surface of anatase [24]. Although O-vacancies have been vastly modeled in anatase and rutile [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41], to the best of the authors' knowledge, theoretical studies have not considered/compared double O-vacancy structures of rutile and anatase.…”

Section: Introductionmentioning

confidence: 99%

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Dispersion of Defects in TiO2 Semiconductor: Oxygen Vacancies in the Bulk and Surface of Rutile and Anatase

Elahifard¹,

Sadrian

Mirzanejad

et al. 2020

Catalysts

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Oxygen deficiency (O-vacancy) contributes to the photoefficiency of TiO2 semiconductors by generating electron rich active sites. In this paper, the dispersion of O-vacancies in both bulk and surface of anatase and rutile phases was computationally investigated. The results showed that the O-vacancies dispersed in single- and double-cluster forms in the anatase and rutile phases, respectively, in both bulk and surface. The distribution of the O-vacancies was (roughly) homogeneous in anatase, and heterogenous in rutile bulk. The O-vacancy formation energy, width of defect band, and charge distribution indicated the overlap of the defect states in the rutile phase and thus eased the formation of clusters. Removal of the first and the second oxygen atoms from the rutile surface took less energy than the anatase one, which resulted in a higher deficiency concentration on the rutile surface. However, these deficiencies formed one active site per unit cell of rutile. On the other hand, the first O-vacancy formed on the surface and the second one formed in the subsurface of anatase (per unit cell). Supported by previous studies, we argue that this distribution of O-vacancies in anatase (surface and subsurface) could potentially create more active sites on its surface.

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Section: O-vacancy In the Bulk Structure Of Rutile And Anatasesupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Dispersion of Defects in TiO2 Semiconductor: Oxygen Vacancies in the Bulk and Surface of Rutile and Anatase

Elahifard¹,

Sadrian

Mirzanejad

et al. 2020

Catalysts

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“…One should be aware that the symmetries may not be exact because of distortion of the atomic positions from high symmetries on account of chemical bonding. In rutile TiO 2 there is some mixing between orbitals associated with the t 2g and e g symmetries, but that is included in our theory [32,47,81]. In typical materials, such as transitionmetal oxides, the t 2g -e g splitting is on the order of eV.…”

Section: Theoretical Frameworkmentioning

confidence: 99%

Electron-phonon coupling in d -electron solids: A temperature-dependent study of rutile TiO2 by first-principles theory and two-photon photoemission

Shang

Argondizzo

Tan

et al. 2019

Phys. Rev. Research

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is a paradigmatic transition-metal oxide with applications in optics, electronics, photocatalysis, etc., that are subject to pervasive electron-phonon interaction. To understand how energies of its electronic bands, and in general semiconductors or metals where the frontier orbitals have a strong d-band character, depend on temperature, we perform a comprehensive theoretical and experimental study of the effects of electron-phonon (e-p) interactions. In a two-photon photoemission (2PP) spectroscopy study we observe an unusual temperature dependence of electronic band energies within the conduction band of reduced rutile TiO 2 , which is contrary to the well-understood sp-band semiconductors and points to a so far unexplained dichotomy in how the e-p interactions affect differently the materials where the frontier orbitals are derived from the sp-and d orbitals. To develop a broadly applicable model, we employ state-of-the-art first-principles calculations that explain how phonons promote interactions between the Ti-3d orbitals of the conduction band within the octahedral crystal field. The characteristic difference in e-p interactions experienced by the Ti-3d orbitals of rutile TiO 2 crystal lattice are contrasted with the more familiar behavior of the Si-2s orbitals of stishovite SiO 2 polymorph, in which the frontier 2s orbital experiences a similar crystal field with the opposite effect. The findings of this analysis of how e-p interactions affect the d-and sp-orbital derived bands can be generally applied to related materials in a crystal field. The calculated temperature dependence of d-orbital derived band energies agrees well with and explains the temperature-dependent inter-d-band transitions recorded in 2PP spectroscopy of TiO 2. The general understanding of how e-p interactions affect d-orbital derived bands is likely to impact the understanding of temperature-dependent properties of highly correlated materials.

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“…The Ti-O-Ti angle is155.4º for the TiO2(A) and 130.4º and 99.1º for the TiO2(R). Shortly, by changing the substrate from STO to TiO2(A) and then to TiO2(R), we can continuously decrease the Ti-O-Ti angle, thus tune the hybridization between O2p and Ti3d eg orbitals 30.…”

mentioning

confidence: 99%

Tuning the Two-Dimensional Electron Gas at Oxide Interfaces with Ti–O Configurations: Evidence from X-ray Photoelectron Spectroscopy

Gan

Niu

Norrman

et al. 2017

ACS Appl. Mater. Interfaces

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A chemical redox reaction can lead to a two-dimensional electron gas at the interface between a TiO-terminated SrTiO (STO) substrate and an amorphous LaAlO capping layer. When replacing the STO substrate with rutile and anatase TiO substrates, considerable differences in the interfacial conduction are observed. On the basis of X-ray photoelectron spectroscopy (XPS) and transport measurements, we conclude that the interfacial conduction comes from redox reactions, and that the differences among the materials systems result mainly from variations in the activation energies for the diffusion of oxygen vacancies at substrate surfaces.

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Oxygen-vacancy driven electron localization and itinerancy in rutile-based TiO2

Cited by 21 publications

References 85 publications

Dispersion of Defects in TiO2 Semiconductor: Oxygen Vacancies in the Bulk and Surface of Rutile and Anatase

Dispersion of Defects in TiO2 Semiconductor: Oxygen Vacancies in the Bulk and Surface of Rutile and Anatase

Electron-phonon coupling in d -electron solids: A temperature-dependent study of rutile TiO2 by first-principles theory and two-photon photoemission

Tuning the Two-Dimensional Electron Gas at Oxide Interfaces with Ti–O Configurations: Evidence from X-ray Photoelectron Spectroscopy

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