Properties of rutile TiO2 surfaces from a Tight-Binding Variable-Charge model. Comparison with ab initio calculations

Hallil, A.; Amzallag, E.; Landron, Sylvain; Tétot, R.

doi:10.1016/j.susc.2011.01.010

Cited by 20 publications

(26 citation statements)

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“…in the Swamy-Gale model 57,58 . Hallil et al have corrected the deficiency in the QEq approach by changing the functional form of the covalent interactions, by 70 using a pair-functional form to describe Ti-O covalent bonds 59,60 . This provides a more responsive description of the short-range bonding terms, and allows the variable-charge advantage of the QEq scheme to be retained 60 .…”

Section: Methodsmentioning

confidence: 99%

“…This modification better reproduces the very small changes seen in oxygen charge found with DFT+U; further details can be found in refs. 56,59,60 .…”

Section: Methodsmentioning

confidence: 99%

“…In addition, we previously showed that sub-nm diameter (TiO 2 ) n clusters, with n=2-4, adsorbed on the rutile TiO 2 (110) surface can lead to a 55 reduced band gap compared to pure rutile TiO 2 , which should enhance the photocatalytic activity in these heterostructures 35 , although a focus in that paper was on the reactivity of these structures. DFT simulations have also shown that modifying the rutile (110) surface with small transition metal oxide 60 nanoclusters, e.g. Cr 2 O 3 , Mo 2 O 4 , could also lead to a band gap reduction 36 .…”

Section: Introductionmentioning

confidence: 99%

“…Minimised TiO 2 clusters were created using the parallel tempering technique 61 with the charge equilibration (QEq) potential 59,60 . The initial positions of the ions in the cluster were randomly chosen, followed by 90 Monte Carlo simulation in an ordered series of replicas 1,2,…N.…”

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confidence: 99%

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TiO2 nanocluster modified-rutile TiO2 photocatalyst: a first principles investigation

2013

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Access to the full text of the published version may require a subscription. The clusters adsorb strongly at the surface giving adsorption energies from -2.7 eV to -6.7 eV. The resulting structures show a large number of new Ti-O bonds created between the cluster and the surface, so that the new bonds enhance the stability. The electronic density of states (EDOS) shows that the valence band edge is shifted upwards, due to new nanocluster derived states in this region, while the conduction band is unchanged and composed of the Ti 3d states from the surface. This 20 reduces the band gap over bare TiO 2 , potentially shifting light absorption into the visible region. The valence and conduction band composition of these heterostructures will favour spatial separation of electrons and holes after light excitation, thus giving improved photocatalytic properties in these novel structures. Rights © The Royal Society of Chemistry 2013. This is the Accepted Manuscript version of a published work that appeared in final form25

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Section: Methodsmentioning

confidence: 99%

“…This modification better reproduces the very small changes seen in oxygen charge found with DFT+U; further details can be found in refs. 56,59,60 .…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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confidence: 99%

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TiO2 nanocluster modified-rutile TiO2 photocatalyst: a first principles investigation

2013

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“…The SMTB-Q (for second-moment tight-binding QEq) model is a new transferable variable-charge model aimed at describing the stability, structure and defects formed in the bulk and at oxide surfaces [24,25,29]. This model allows one to vary ion charges and to take into account both the ionic and covalent character of bonds [24,25].…”

Section: Brief Description Of the Smtb-q Modelmentioning

confidence: 99%

Phase Transformations in Pyrochlores Irradiated with Swift Heavy Ions: Influence of Composition and Chemical Bonding

et al. 2013

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Gd2Ti2O7 and Gd2Zr2O7 pyrochlores were irradiated with swift heavy ions in order to investigate the eects of the chemical composition on the structural changes induced by high electronic excitation. The XRD results show that the structural modications induced by irradiation with 93 MeV Xe ions are strongly dependent on the sample composition: Gd2Ti2O7 is readily amorphized, whereas Gd2Zr2O7 is transformed into a radiation-resistant anion-decient uorite structure. Atomistic simulations with the second-moment tight-binding QEq model allow us to calculate the lattice properties of both Gd2Ti2O7 and Gd2Zr2O7, and also to quantify the degree of covalency and ionicity in these compounds. These calculations clearly show that Gd2Ti2O7 is more covalent than Gd2Zr2O7, thus conrming that the amorphization resistance can be related to the covalent character of insulators.

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Defect‐Mediated Anisotropic Lattice Expansion in Ceramics as Evidence for Nonthermal Coupling between Electromagnetic Fields and Matter

et al. 2019

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Electromagnetic (EM) fields can trigger a range of surprising responses in materials. Microwave radiation (MWR), a type of EM field in the frequency range of 0.3–300 GHz, can lower the synthesis temperature required for ceramics such as TiO2 and induces mixed amorphous–crystalline phase compositions. To better understand the effects of MWR on matter, structural changes during microwave heating and MWR‐assisted synthesis using in situ synchrotron X‐ray diffraction are studied. Anisotropic expansion–contraction of lattice parameters under microwave‐radiation is observed, which contradicts the results from conventional thermal heating. When as‐received TiO2 powders are heated with MWR, an instantaneous decrease in the intensities of diffraction peaks indicates decrystallization/amorphization. High‐resolution electron microscopy supports these observations. Raman spectroscopy and X‐ray photoemission spectroscopy indicate increased defect‐generation under microwave exposure. Molecular dynamics simulations on the anatase phase of TiO2 suggests that introducing an oxygen vacancy can lead to the formation of an interstitial–vacancy pair resulting in anisotropic expansion–contraction of the lattice. These unique responses of ceramics under externally applied fields provide direct evidence for nonthermal coupling between EM fields and matter. Understanding such nonthermal, field‐driven processes has implications in engineering low‐temperature processes for integrating ceramics with polymers for flexible electronics, energy harnessing, and storage applications.

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Properties of rutile TiO2 surfaces from a Tight-Binding Variable-Charge model. Comparison with ab initio calculations

Cited by 20 publications

References 58 publications

TiO2 nanocluster modified-rutile TiO2 photocatalyst: a first principles investigation

TiO2 nanocluster modified-rutile TiO2 photocatalyst: a first principles investigation

Phase Transformations in Pyrochlores Irradiated with Swift Heavy Ions: Influence of Composition and Chemical Bonding

Defect‐Mediated Anisotropic Lattice Expansion in Ceramics as Evidence for Nonthermal Coupling between Electromagnetic Fields and Matter

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