First-principles studies on phase stability of TiO2 by using GGA+U calculations

Samat, Mohd Hazrie; Taib, Mohamad Fariz Mohamad; Jaafar, N. K.; Hassan, Oskar Hasdinor; Yahya, Muhd Zu Azhan; Ali, Ab Malik Marwan

doi:10.1063/1.5066699

Cited by 12 publications

(5 citation statements)

References 26 publications

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“…On the other hand, the DFT-MBD calculation provided an excellent agreement with the experimental data [40]. Similarly, Samat et al [42] have investigated the phase stability of rutile, anatase and brookite using DFT and DFT+U methods from CASTEP computer code calculations. The results obtained with GGA-PBEsol showed that anatase is more stable than rutile and brookite, which disagrees with experimental reports.…”

Section: An Overview Of Theoretically Investigated Tiomentioning

confidence: 64%

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AX2: Type of compounds and an overview of theoretically investigated TiO2

Jovanović¹,

Zagorac²,

Matović³

et al. 2020

Adv Techol

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AX 2-type compounds can be ionic, covalent or molecular types of structure, which depends on the size of atoms and the polarization properties. The materials of such type of the structure have different properties that can find the application in various areas of science and industry. Titanium dioxide, as a material of AX 2-type of the structure is a wide band gap semiconductor that has been widely investigated due to its photocatalytic properties and applicability for various purposes, such as the production of solar cells, decontamination of pollutants, elimination of microorganisms, suppression of cancer cells, etc. Experimental and theoretical studies of this metal oxide can give different data on the stability of individual crystalline modifications and their transitions. This study has presented an overview of theoretically examined TiO 2 modifications and current problems that can be encountered (such as various band gap values obtained by different methods and functionals; the difference between the stability of modifications examined on ab initio level and experimentally; the character of chemical bonds and transitions at the specific temperature and pressure conditions…) and overrun by optimal corrections added in calculations.

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Section: An Overview Of Theoretically Investigated Tiomentioning

confidence: 64%

“…The results obtained with GGA-PBEsol showed that anatase is more stable than rutile and brookite, which disagrees with experimental reports. As a solution, the authors found that the better agreement was achieved with calculations obtained using GGA-PBEsol+U [42].…”

Section: An Overview Of Theoretically Investigated Tiomentioning

confidence: 94%

AX2: Type of compounds and an overview of theoretically investigated TiO2

Jovanović¹,

Zagorac²,

Matović³

et al. 2020

Adv Techol

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“…The optical absorption of anatase occur in the ultraviolet wavelength range at an absorption edge between 300 and 400 nm. Above 400 nm the anatase absorption coefficient is very low, as showen by 20 The absorption of lower energy photons in the infrared range happens primarily through weakly-bound electrons available to move through the crystalline structure 19 , which, when in appropriate quantity, keep the transmittance of bulk-like glass and anatase TiO 2 . On the other hand, below 400 nm, there is a shift in the falling edge of transmittance.…”

Section: Resultsmentioning

confidence: 99%

The Role of HiPIMS Pulse Length in Reactive Deposition of Transparent Conductive Oxide Nb:TiO2 Films

Stryhalski,

Laur,

Sagás

et al. 2023

Mat. Res.

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The present paper sets out to investigate the role of voltage pulse length on the properties of Nb:TiO 2 films deposited by High Power Impulse Magnetron Sputtering (HiPIMS). Several characteristics of the films were investigated, namely, resistivity, transmittance, crystallinity and band gap values of Nb:TiO 2 films. Reactive depositions were carried out in Ar/O 2 plasma with 40 µs, 50 µs, 60 µs, and 70 µs pulses. Increasing the pulse length changes the deposition from compound to metal mode. As it gets closer to metal mode, the deposition rate increases by up to one order of magnitude, while the resistivity of the resulting Nb:TiO 2 film becomes as low as 10 -4 Ω.cm, without any significant loss in optical transmittance, which remains close to 90% for a wavelength around 450 nm, but reduction in 25% of heat transmission (above 800 nm) were observed. Results indicate the anatase phase for all deposition conditions, and Ti 3+ states increase with the pulse length, which can be explained by the generation of a second band gap. Both the niobium doping and the Ti 3+ states can contribute to increase the conductivity of the Nb:TiO 2 films in the as-deposited condition.

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“…TiO 2 NPs exist in three different structures: as anatase, rutile, and brookite (2) (Figure 1. ), which differ in their crystal structure where the Ti-O bond length ranges are 1.931-2.004 Å for rutile, 1.914-2.005 Å for anatase and 1.850-2.099 Å for brookite (3).…”

Section: Introductionmentioning

confidence: 98%

Evaluation of the permeability and in vitro cytotoxicity of functionalized titanate nanotubes on Caco-2 cell line

Ranjous

Kósa

Ujhelyi

et al. 2021

APH

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Titanate nanotubes (TNTs) are promising vectors for drug delivery due to their unique physicochemical properties such as biocompatibility, mechanical strength, and chemical resistivity. However, considering their strong hydrophilicity, pristine TNTs exert very limited permeability through the intestinal cell layer. The aim of this study was to turn the surface characteristics and thus enhance the permeability of TNTs by functionalization. TNTs were functionalized with trichloro(octyl)silane (TCOS) and magnesium stearate (MgSt). Carbon content and surface free energy of the functionalized TNTs were detected to evaluate the effectiveness of functionalization, by using CHNS analytical and optical contact angle (OCA) measurements, respectively. Caco-2 cell line was applied to test the permeability and the cytotoxicity of the samples. Cytotoxicity was evaluated by using MTT assay. The results revealed that the surface characteristics of TNTs may be adjusted in a wider range with TCOS-TNT than with St, but the samples show higher toxicity. Silane functionalized TNTs may be safe up to 1 mg/ml, while St functionalized TNTs up to 2 mg/ml concentration. The preparation method of MgSt-TNT was also superior from the aspect of environmental safety. The permeability was suitable for samples with moderate hydrophobicity (aqueous contact angle 60-90°).

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First-principles studies on phase stability of TiO2 by using GGA+U calculations

Cited by 12 publications

References 26 publications

AX2: Type of compounds and an overview of theoretically investigated TiO2

AX2: Type of compounds and an overview of theoretically investigated TiO2

The Role of HiPIMS Pulse Length in Reactive Deposition of Transparent Conductive Oxide Nb:TiO2 Films

Evaluation of the permeability and in vitro cytotoxicity of functionalized titanate nanotubes on Caco-2 cell line

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