Oxygen vacancy in cubic WO3 studied by first-principles pseudopotential calculation

Karazhanov, Smagul; Zhang, Yong; Mascarenhas, A.; Deb, S. K.; Wang, L.-W.

doi:10.1016/j.ssi.2003.08.012

Cited by 32 publications

(21 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, the optical band gap of the WO 3 annealed at the range from 200 to 500 ∘ C is increased up to 3.15 eV due to recrystallization of the film. The reasons for which becomes bigger than 2.7 eV is the formation of oxygen vacancies at hese temperatures and the change of crystalline phase, as can be seen in Figure 8 [33,34]. It is worth noting that has reported in the literature that for WO 3 films deposited by evaporation has found 2.7 < < 3.5 eV [1].…”

Section: Resultsmentioning

confidence: 88%

Characterization of WO₃Thin Films Grown on Silicon by HFMOD

Dı́az-Reyes

Castillo-Ojeda

Galván-Arellano

et al. 2013

Advances in Condensed Matter Physics

View full text Add to dashboard Cite

We studied the effect of annealing temperature on the physical properties of WO3thin films using different experimental techniques. WO3has been prepared by hot-filament metal oxide deposition (HFMOD). The films, chemical stoichiometry was determined by X-ray photoelectron spectroscopy (XPS). The monoclinic single-phase nature of the as-deposited films, structure was changed to triclinic structure by annealing them at higher temperatures than 400°C, which has been determined by the X-ray diffraction analysis. By Raman scattering is confirmed the change of crystalline phase, of monoclinic to triclinic, since that lattice vibrational modes of as-deposited WO3and annealed at 500°C present clearly differences. WO3band gap energy can be varied from 2.92 to 3.15 eV by annealing WO3from 0 to 500°C as was obtained by transmittance measurements. The photoluminescence response of the as-deposited film presents three radiative transitions observed at 2.85, 2.41, and 2.04 eV that could be associated with oxygen vacancies; the first one is shifted to higher energies as the annealing temperature is increased due to the change of crystalline phase of the WO3.

show abstract

Section: Resultsmentioning

confidence: 88%

Characterization of WO₃Thin Films Grown on Silicon by HFMOD

Dı́az-Reyes

Castillo-Ojeda

Galván-Arellano

et al. 2013

Advances in Condensed Matter Physics

View full text Add to dashboard Cite

show abstract

“…The decrement of particles size increases the optical band gap energy of the nanoparticles, indicating the presence of quantum confinement effect, which is consistent with previous theoretical argument by Brus [11] . Karazhanov [12] showed an oxygen (anion) vacancy in WO 3 does not only generate a donor like state near the fundamental band gap, derived from the top valence bands, but also gives rise to an additional pair of defect states: A hyper-deep resonant state in the valence band and a high-lying resonant state in the conduction band, derived from s-like bonding and antibonding bands, respectively. We assume that the transition in mentioned bands offers a possible explanation for the observed peaks in UV-V is spectra of WO 3 .…”

Section: Resultsmentioning

confidence: 99%

Preparation of WO3 Nanoparticles Using Cetyl Trimethyl Ammonium Bromide Supermolecular Template

Radiman¹,

Yarmo²

2009

American J. of Applied Sciences

View full text Add to dashboard Cite

Problem statement: WO 3 is one of the most interested metal oxides because of its application as catalysts, sensors, electrochromic devices, ceramic, solar cell, pigments and so on. More investigation is needed to find the good and low cost method for preparation of WO 3 nanoparticles with uniform morphology and narrow distribution using a surfactant mediated method. Approach: In this study, the synthesis of WO 3 nanoparticles was accomplished using a cationic surfactant (cetyl trimethyl ammonium bromide) as the organic supermolecular template and WCl 6 and NH 4 OH as the inorganic precursor and counter ion source, respectively. The effects of reaction temperature and surfactant concentration in particle size of resultant WO 3 nanoparticles were investigated. Results: The different ranges of particle size and size distribution were obtained using different surfactant concentration and reaction temperature. The WO 3 particles in the nanometer range (3-15 nm) with uniform morphology and narrow distribution were obtained by optimization of reaction condition. Xray diffraction, transmission electron microscopy, variable pressure scanning electron microscope, Xray photoelectron spectroscopy and UV-Vis spectroscopy were used to characterize the final products. The nanomaterials WO 3 showed different pattern in UV-Vis spectroscopy compare to the bulk WO 3 . Conclusion: A relatively simple and effective procedure for synthesis of WO 3 nanoparticles with mean size below 10 nm, narrow size distribution and high monodispersity using CTAB supramolecular template had been developed and optimized.

show abstract

“…These vacancies in WO 3 can generate three types of defect states, a hyperdeep one associated with the s-like bonding band, a highlying one associated with the s-like antibonding band, and a donor state associated with the valence bands near the fundamental band gap. 34 It is also noted that, with a decrease in the intensity of NUV peaks, peak intensity corresponding to band to band transition at the wavelength of 485 nm is increased.…”

Section: Optical Studiesmentioning

confidence: 95%

Effect of Substrate Temperature on the Properties of Sprayed WO3 Thin Films Using Peroxotungstic Acid and Ammonium Tungstate: A Comparative Study

Ganbavle

Kim

Rajpure

2015

Journal of Elec Materi

View full text Add to dashboard Cite

A comparative study on the physicochemical properties of tungsten oxide (WO 3 ) thin films synthesized using peroxotungstic acid (PTA) and ammonium tungstate (AT) by simple spray pyrolysis technique is reported. X-ray diffraction patterns show that the films deposited using both the precursors are polycrystalline with monoclinic crystal structure. The x-ray photoelectron spectroscopy studies confirm that the films are sub-stoichiometric with O/W ratios of 2.93 and 2.87, respectively, for typical PTA and AT films. Tungsten (W) exists in two chemical states, 5+ and 6+. Scanning electron microscopy images show the uniform and dense network of wires in PTA films, while the films deposited using AT possess a porous structure with small grains. Electrical and dielectric studies show that films are highly resistive and possess high dielectric constant. The near ultra-violet, blue, green and weak red emissions due to defects were observed in the photoluminescence studies. Properties of the WO 3 thin films reported here are suitable for gas sensor applications. Films deposited using PTA are more functional than those deposited using AT.

show abstract

Oxygen vacancy in cubic WO3 studied by first-principles pseudopotential calculation

Cited by 32 publications

References 26 publications

Characterization of WO₃Thin Films Grown on Silicon by HFMOD

Characterization of WO₃Thin Films Grown on Silicon by HFMOD

Preparation of WO3 Nanoparticles Using Cetyl Trimethyl Ammonium Bromide Supermolecular Template

Effect of Substrate Temperature on the Properties of Sprayed WO3 Thin Films Using Peroxotungstic Acid and Ammonium Tungstate: A Comparative Study

Contact Info

Product

Resources

About

Oxygen vacancy in cubic WO3 studied by first-principles pseudopotential calculation

Cited by 32 publications

References 26 publications

Characterization of WO3Thin Films Grown on Silicon by HFMOD

Characterization of WO3Thin Films Grown on Silicon by HFMOD

Preparation of WO3 Nanoparticles Using Cetyl Trimethyl Ammonium Bromide Supermolecular Template

Effect of Substrate Temperature on the Properties of Sprayed WO3 Thin Films Using Peroxotungstic Acid and Ammonium Tungstate: A Comparative Study

Contact Info

Product

Resources

About

Characterization of WO₃Thin Films Grown on Silicon by HFMOD

Characterization of WO₃Thin Films Grown on Silicon by HFMOD