Kinetic study on preparation of substoichiometric tungsten oxide WO2.72 via hydrogen reduction process

Qiao, Dan; Wang, Yue; Li, Fan; Wang, Daya; Yan, Baijun

doi:10.1007/s10973-018-7966-4

Cited by 10 publications

(6 citation statements)

References 21 publications

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“… 92 , 93 The second degradation period, above 773 K, is present mainly for BCW since only it has a large amount of W 4+ ions prone to fast oxidation toward W 5+/6+ which are the main ingredients of CCWO at that point. 94 − 96 Unstable WO 3– x species containing 5+ ions have a higher heat-tolerance factor but will also start oxidizing since their decomposition barrier does not fall much above that threshold, though at a much slower pace. 53 , 95 , 96 Hence, those continuous, downward slopes in DSC and TG graphs ( Figure 10 b,d) experience slight fluctuations and changes in their curvature above 900 K—possible, minor Ce 4+ /W 5+ phases might already form by then.…”

Section: Resultsmentioning

confidence: 99%

Synthesis Attempt and Structural Studies of Novel A₂CeWO₆ Double Perovskites (A²⁺ = Ba, Ca) in and outside of Ambient Conditions

et al. 2022

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This comprehensive work showcases two novel, rock-salt-type minerals in the form of amphoteric cerium–tungstate double perovskite and ilmenite powders created via a high-temperature solid-state reaction in inert gases. The presented studies have fundamental meaning and will mainly focus on a detailed synthesis description of undoped structures, researching their possible polymorphism in various conditions and hinting at some nontrivial physicochemical properties like charge transfer for upcoming optical studies after eventual doping with selectively chosen rare-earth ions. The formerly mentioned, targeted A 2 BB′X 6 group of compounds contains mainly divalent alkali cations in the form of XII A = Ba 2+ , Ca 2+ sharing, here, oxygen-arranged clusters ( II X = O 2– ) with purposely selected central ions from f-block VI B = Ce 4/3+ and d-block VI B′ = W 4/5/6+ since together they often possess some exotic properties that could be tuned and implemented into futuristic equipment like sensors or energy converters. Techniques like powder XRD, XPS, XAS, EPR, Raman, and FTIR spectroscopies alongside DSC and TG were involved with an intent to thoroughly describe any possible changes within these materials. Mainly, to have a full prospect of any desirable or undesirable phenomena before diving into more complicated subjects like: energy or charge transfer in low temperatures; to reveal whether or not the huge angular tilting generates large enough dislocations within the material’s unit cell to change its initial properties; or if temperature and pressure stimuli are responsible for any phase transitions and eventual, irreversible decomposition.

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Section: Resultsmentioning

confidence: 99%

Synthesis Attempt and Structural Studies of Novel A₂CeWO₆ Double Perovskites (A²⁺ = Ba, Ca) in and outside of Ambient Conditions

et al. 2022

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“…The chemical reaction between tungsten and water molecules has also been evaluated thermodynamically. Based on the chemical physics studies 39 , 40 , the only reactions (to the best of knowledge) between the tungsten and the water molecule were endothermic process with apparent activation energy that was estimated to be 132.7 ± 1.1 kJ mol −1 40 . This extent of energy can easily be provided by thermionic emission.…”

Section: Resultsmentioning

confidence: 99%

Fluorescent lamp tungsten filament thermionic emission gun as a novel humidity optical sensor

Torabi-Monfared

Sherafat

Doroodmand

et al. 2021

Sci Rep

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Detecting humidity have been remained a continuing concern within some important areas such as structural health, food processing, industrial as well as agricultural products. In this study, a novel humidity optical sensor is introduced based on the thermionic emission of tungsten filament using the fluorescent lamp set-up. Estimated blue compliant using a charged coupling device camera in optical image of the tungsten filament was confirmed as an appropriate detection system for relative humidity (RH) sensing. The fabricated optical sensor has wide linear range (2.0–98% RH), improved detection limit (< 5.0% RH), acceptable saturated limit (> 99.0% RH), improved percentage of relative standard deviation (4.18%, n = 2), adequate hysteresis (< 4.0% RH) and a shorter rise time (< 5.0 s), respectively. The mechanism behind this detection system is based on the interaction between H2O and tungsten filament during formation of W$${\mathrm{O}}_{3}$$ O 3 .x $${\mathrm{H}}_{2}$$ H 2 O (x = 1–2) in terms of some spectroscopic obtained evidences as well as Fourier transform infrared and X-ray diffraction spectrometries.

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“…It is considered that the Ostwald ripening mechanism plays an important role in the growth of manganese oxide crystals. 37 Moreover, according to XRD patterns, the formation of the rutile TiO 2 phase was also observed when calcined at 400 C. Therefore, it is essential to perform the XPS analysis in order to characterize the chemical composition on the surface of the samples at different calcination temperatures (Fig. 4).…”

Section: Li-o 2 Battery Testsmentioning

confidence: 99%

Effect of the valence state of Mn in MnO_x/Ti₄O₇ composites on the catalytic performance for oxygen reduction reaction and oxygen evolution reaction

Bai

Wang

et al. 2021

RSC Adv.

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Kinetic study on preparation of substoichiometric tungsten oxide WO2.72 via hydrogen reduction process

Cited by 10 publications

References 21 publications

Synthesis Attempt and Structural Studies of Novel A₂CeWO₆ Double Perovskites (A²⁺ = Ba, Ca) in and outside of Ambient Conditions

Synthesis Attempt and Structural Studies of Novel A₂CeWO₆ Double Perovskites (A²⁺ = Ba, Ca) in and outside of Ambient Conditions

Fluorescent lamp tungsten filament thermionic emission gun as a novel humidity optical sensor

Effect of the valence state of Mn in MnO_x/Ti₄O₇ composites on the catalytic performance for oxygen reduction reaction and oxygen evolution reaction

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Kinetic study on preparation of substoichiometric tungsten oxide WO2.72 via hydrogen reduction process

Cited by 10 publications

References 21 publications

Synthesis Attempt and Structural Studies of Novel A2CeWO6 Double Perovskites (A2+ = Ba, Ca) in and outside of Ambient Conditions

Synthesis Attempt and Structural Studies of Novel A2CeWO6 Double Perovskites (A2+ = Ba, Ca) in and outside of Ambient Conditions

Fluorescent lamp tungsten filament thermionic emission gun as a novel humidity optical sensor

Effect of the valence state of Mn in MnOx/Ti4O7 composites on the catalytic performance for oxygen reduction reaction and oxygen evolution reaction

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Synthesis Attempt and Structural Studies of Novel A₂CeWO₆ Double Perovskites (A²⁺ = Ba, Ca) in and outside of Ambient Conditions

Synthesis Attempt and Structural Studies of Novel A₂CeWO₆ Double Perovskites (A²⁺ = Ba, Ca) in and outside of Ambient Conditions

Effect of the valence state of Mn in MnO_x/Ti₄O₇ composites on the catalytic performance for oxygen reduction reaction and oxygen evolution reaction