How the aggregation of oxygen vacancies in rutile-based<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>TiO</mml:mi><mml:mrow><mml:mn>2</mml:mn><mml:mo>−</mml:mo><mml:mi>δ</mml:mi></mml:mrow></mml:msub></mml:math>phases causes memristive behavior

Heckel, Wolfgang; Wehlau, Michael; Maisel, Sascha; Frauenheim, Thomas; Knaup, Jan M.; Müller, Stefan

doi:10.1103/physrevb.92.214104

Cited by 15 publications

(17 citation statements)

References 41 publications

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“…As a consequence, the concentration modulations allow to balance expansive and compressive regions and thereby stabilize the structure, with [103] and [013] being the energetically favorable orientation, as previously reported. 17,26,44,45 These results are also in good agreement with previous calculations for rutile, where planar V O arrangements were discussed to form without strong atomic restructuring, 46 as well as with the general picture of defect ordering in transition metal oxides. 47 In conclusion, we investigated the intrinsic structure of defect arrays in anatase TiO 2 thin films on LAO substrates.…”

Section: T H Isupporting

confidence: 80%

“…The blurring effect attributed to local atomic displacements caused by oxygen vacancies is consistent with the electrostatic relaxation behavior of such point defects in anatase, as predicted theoretically , and also observed experimentally. , The V O induced lattice distortions in anatase are likely compensated by the formation of V O depleted regions and determine a long-range periodic array of modulated V O concentration. As a consequence, the concentration modulations allow to balance expansive and compressive regions and thereby stabilize the structure, with [103] and [013] being the energetically favorable orientation, as previously reported. ,,, These results are also in good agreement with previous calculations for rutile, where planar V O arrangements were discussed to form without strong atomic restructuring, as well as with the general picture of defect ordering in transition metal oxides …”

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confidence: 88%

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Unveiling Oxygen Vacancy Superstructures in Reduced Anatase Thin Films

et al. 2020

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Oxygen vacancies are known to play a crucial role in tuning the physical properties and technological applications of titanium dioxide TiO2. Over the last decades, defects in substoichiometric TiO2 have been commonly associated with the formation of Ti n O2n–x Magnéli phases, which are extended planar defects originating from crystallographic shear planes. By combining advanced transmission electron microscopy techniques, electron energy-loss spectroscopy and atomistic simulations, we reach new understanding of the oxygen vacancy induced structural modulations in anatase, ruling out the earlier shear-plane model. Structural modulations are instead shown to be due to the formation of oxygen vacancy superstructures that extend periodically inside the films, preserving the crystalline order of anatase. Elucidating the structure of oxygen defects in anatase is a crucial step for improving the functionalities of such material system and to engineer devices with targeted properties.

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Section: T H Isupporting

confidence: 80%

supporting

confidence: 88%

Unveiling Oxygen Vacancy Superstructures in Reduced Anatase Thin Films

et al. 2020

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“…Since the Magnéli phases are conductive at room temperature, a Magnéli filament structure is generally believed to be prerequisite for the resistive switching effect of TiO 2 [18]. However, there is increasing theoretical evidence that different types of V O arrangements rather than Magnéli phases, such as the one-dimensional (1D) V O chain in the (1 1 0) plane, can also derive memristive effects in TiO 2 [19][20][21]. To date, experimental identification and the resulting physical nature of this type of V O chain remain lacking.…”

Section: Introductionmentioning

confidence: 99%

Metastable oxygen vacancy ordering state and improved memristive behavior in TiO2 crystals

Hong

Yang

et al. 2020

Science Bulletin

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Theoretical calculation and experimental study of influence of oxygen vacancy on the electronic structure and hemocompatibility of rutile TiO a b s t r a c t Oxygen vacancy is one of the pivotal factors for tuning/creating various oxide properties. Understanding the behavior of oxygen vacancies is of paramount importance. In this study, we identify a metastable oxygen vacancy ordering state other than the well-known Magnéli phases in TiO 2 crystals from both experimental and theoretical studies. The oxygen vacancy ordering is found to be a zigzag chain along the [0 0 1] direction in the (1 1 0) plane occurring in a wide temperature range of 200-500°C. This metastable ordering state leads to a first-order phase transition accompanied by significant enhancement of dielectric permittivity and a memristive effect featuring a low driving electric field. Our results can improve oxide properties by engineering oxygen vacancies.

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“…[1][2][3][4][5][6][7] Second, on the search of realizing a memristor, 8 TiO 2−δ remains a key material. 9,10 Formation and migration of oxygen-vacancy defects are identified to regulate the resistance modulation therein.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2017

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Oxygen-deficient TiO2 in the rutile structure as well as the Ti3O5 Magnéli phase is investigated within the charge self-consistent combination of density functional theory (DFT) with dynamical mean-field theory (DMFT). It is shown that an isolated oxygen vacancy (VO) in titanium dioxide is not sufficient to metallize the system at low temperatures. In a semiconducting phase, an ingap state is identified at ε IG ∼ −0.75 eV in excellent agreement with experimental data. Bandlike impurity levels, resulting from a threefold VO-Ti coordination as well as entangled (t2g, eg) states, become localized due to site-dependent electronic correlations. Charge localization and strong orbital polarization occur in the VO-near Ti ions, which details can be modified by a variation of the correlated subspace. At higher oxygen vacancy concentration, a correlated metal is stabilized in the Magnéli phase. A VO-defect rutile structure of identical stoichiometry shows key differences in the orbital-resolved character and the spectral properties. Charge disproportionation is vital in the oxygen-deficient compounds, but obvious metal-insulator transitions driven or sustained by charge order are not identified. arXiv:1703.05543v2 [cond-mat.mtrl-sci]

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How the aggregation of oxygen vacancies in rutile-basedTiO2−δphases causes memristive behavior

Cited by 15 publications

References 41 publications

Unveiling Oxygen Vacancy Superstructures in Reduced Anatase Thin Films

Unveiling Oxygen Vacancy Superstructures in Reduced Anatase Thin Films

Metastable oxygen vacancy ordering state and improved memristive behavior in TiO2 crystals

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

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