The structure and electrical conductivity of vacuum-annealed WO3 thin films

Gillet, M.; Aguir, Khalifa; Lemire, Céline; Gillet, E.; Schierbaum, K.D.

doi:10.1016/j.tsf.2004.04.018

Cited by 126 publications

(74 citation statements)

References 41 publications

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“…The conductivity is calculated from the experimentally determined resistance R, which is monitored during the three heating and cooling cycles. The activation energy of conduction, E A , was frequently interpreted using the Arrhenius equation between 300 and 700 K. Our results are compatible with the principle results of conductivity of WO 3−x thin films [19][20][21][22][23][24][25][26]. It is obtained from the following formula:…”

Section: Resultssupporting

confidence: 86%

“…In WO 3−x NPs with CS phases, we suppose that the conductivity of tungsten oxide NPs is governed by the non-stoichiometry of WO 3 considered as n-type semiconductor and assumed that the non-stoichiometry originates only from oxygen vacancies of WO 6 octahedral. The conductivity curve exhibits a slope similar to the one obtained for annealing WO 3 thin films in low oxygen pressure [19][20][21][22][23]. This indicates that the NPs keep the same structure characterized by a high density of oxygen vacancies [20][21][22][23][24].…”

Section: Resultssupporting

confidence: 58%

“…3. The observed DC electrical conductivity of WO 3 NPs acts as the polycrystalline n-type semiconductor behaviour [19][20][21][22] with an activation energy of about 0.56(2) eV. Figure 4 represents the variation of activation energy σ of WO 3 NPs using milling processes A and B at the stable WO 3−x phases.…”

Section: Resultsmentioning

confidence: 99%

“…It has been observed that during the first milling time, the conductivity value undergoes large variations, which could be explained either by structural modification effects (process A) [19] or by hydrogen interaction with WO 6 octahedral (process B). In WO 3−x NPs with CS phases, we suppose that the conductivity of tungsten oxide NPs is governed by the non-stoichiometry of WO 3 considered as n-type semiconductor and assumed that the non-stoichiometry originates only from oxygen vacancies of WO 6 octahedral.…”

Section: Resultsmentioning

confidence: 99%

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Synthesis, Separation and Electrical Properties of WO_3-xNanopowders via Partial Pressure High Energy Ball-Milling

Mohammad

2009

Acta Phys. Pol. A

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Reduction processes of WO 3 nanopowder either with carbon or with hydrogen were observed using X-ray powder diffraction and transmission electron microscope. The phase transformations, separation, grain size and electrical conductivity of WO 3−x nanopowder during reductions via partial pressure high energy ball-milling have been studied. During the carbon-reduction process the monoclinic WO3 structure transforms to nonstoichiometric Magneli phases W40O118, WO2.9 and finally to WO2 and W mixed phases. The Magneli WO3−x phases exhibit specific fringe contrast imaging of well-ordered crystallographic shear planes. In comparison, the monoclinic WO3 structure transforms to hydrate WO3·1/3H2O, hexagonal WO3, non-stoichiometric WO2.7 and finally to WO2 and W mixed phases during the hydrogen-reduction process. The inclusion of hydrogen atoms between the WO6 octahedral structure shifts the reduction steps to lower milling times. It demonstrates that the formation of hydrate WO3 phases enhances the amenability of the system to reduction. The activation energy for conduction was deduced from the Arrhenius equation and was found to depend on oxygen partial pressure or presence of the hydrogen atoms. The defect band model was used for interpretation of these behaviors. It supposes that the surface oxygen vacancies introduce donor levels in the gap of semiconductor, so free electrons are produced by reduction.

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Section: Resultssupporting

confidence: 86%

Section: Resultssupporting

confidence: 58%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Synthesis, Separation and Electrical Properties of WO_3-xNanopowders via Partial Pressure High Energy Ball-Milling

Mohammad

2009

Acta Phys. Pol. A

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“…3 are also known to display reactivity toward cyclohexane oxidation, although with lower efficiency 45 due to reduced lattice oxygen mobility. 46,47 In this case, we observed a simplified spectrum of spin adducts moving from MoO 3 to WO 3 including a reduced overall intensity accompanied by complete disappearance of the parent C 6 H 11 · radical for the latter catalyst, which is considered responsible for the initiation step for this reaction ͑Fig. 10͒.…”

Section: Initiationmentioning

confidence: 85%

A catalytic reactor for the trapping of free radicals from gas phase oxidation reactions

Conte

Wilson

Chechik

2010

Review of Scientific Instruments

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A catalytic reactor for the trapping of free radicals originating from gas phase catalytic reactions is described and discussed. Radical trapping and identification were initially carried out using a known radical generator such as dicumyl peroxide. The trapping of radicals was further demonstrated by investigating genuine radical oxidation processes, e.g., benzaldehyde oxidation over manganese and cobalt salts. The efficiency of the reactor was finally proven by the partial oxidation of cyclohexane over MoO 3 , Cr 2 O 3 , and WO 3 , which allowed the identification of all the radical intermediates responsible for the formation of the products cyclohexanol and cyclohexanone. Assignment of the trapped radicals was carried out using spin trapping technique and X-band electron paramagnetic resonance spectroscopy.

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Nanostructured Tungsten Oxide – Properties, Synthesis, and Applications

Zheng

Strano

et al. 2011

Adv Funct Materials

1,274

911

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This section focuses on the fundamental properties of nanostructured WO x and start with its various crystal structures and the conditions for phase transitions between these structures. The structures of nonstoichiometric WO x and WO 3 hydrates Nanostructured Tungsten Oxide -Properties, Synthesis, and Applications Metal oxides are the key ingredients for the development of many advanced functional materials and smart devices. Nanostructuring has emerged as one of the best tools to unlock their full potential. Tungsten oxides (WO x ) are unique materials that have been rigorously studied for their chromism, photocatalysis, and sensing capabilities. However, they exhibit further important properties and functionalities that have received relatively little attention in the past. This Feature Article presents a general review of nanostructured WO x , their properties, methods of synthesis, and a description of how they can be used in unique ways for different applications.

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The structure and electrical conductivity of vacuum-annealed WO3 thin films

Cited by 126 publications

References 41 publications

Synthesis, Separation and Electrical Properties of WO_3-xNanopowders via Partial Pressure High Energy Ball-Milling

Synthesis, Separation and Electrical Properties of WO_3-xNanopowders via Partial Pressure High Energy Ball-Milling

A catalytic reactor for the trapping of free radicals from gas phase oxidation reactions

Nanostructured Tungsten Oxide – Properties, Synthesis, and Applications

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The structure and electrical conductivity of vacuum-annealed WO3 thin films

Cited by 126 publications

References 41 publications

Synthesis, Separation and Electrical Properties of WO3-xNanopowders via Partial Pressure High Energy Ball-Milling

Synthesis, Separation and Electrical Properties of WO3-xNanopowders via Partial Pressure High Energy Ball-Milling

A catalytic reactor for the trapping of free radicals from gas phase oxidation reactions

Nanostructured Tungsten Oxide – Properties, Synthesis, and Applications

Contact Info

Product

Resources

About

Synthesis, Separation and Electrical Properties of WO_3-xNanopowders via Partial Pressure High Energy Ball-Milling

Synthesis, Separation and Electrical Properties of WO_3-xNanopowders via Partial Pressure High Energy Ball-Milling