A new vanadium pentoxide amorphous phase

Gharbi, N.; R’Kha, C.; Ballutaud, D.; Michaud, M.; Livage, Jacques; Audière, Jean-Paul; Schiffmacher, G.

doi:10.1016/0022-3093(81)90003-x

Cited by 24 publications

(12 citation statements)

References 13 publications

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“…We set out to model the glass structure to understand the water durability, thermal stability and hardness, which are important in practical applications. The water durability of VPx glasses improves as the amount of P 2 O 5 increases, even though VP0 (g-V 2 O 5 ) and VP100 (g-P 2 O 5 ) glasses readily dissolve into water 31,42,43 . Gin et al reported on the water durability of glass divided into several stages 44 .…”

Section: Discussionmentioning

confidence: 99%

Controlling oxygen coordination and valence of network forming cations

Aoyagi

Kohara

Naito

et al. 2020

Sci Rep

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Understanding the structure-property relationship of glass material is still challenging due to a lack of periodicity in disordered materials. Here, we report the properties and atomic structure of vanadium phosphate glasses characterized by reverse Monte Carlo modelling based on neutron/synchrotron X-ray diffraction and EXAFS data, supplemented by Raman and NMR spectroscopy. In vanadium-rich glass, the water durability, thermal stability and hardness improve as the amount of P 2 o 5 increases, and the network former of the glass changes from VO x polyhedra to the interplay between VO x polyhedra and po 4 tetrahedra. We find for the first time that the coordination number of oxygen atoms around a V 4+ is four, which is an unusually small coordination number, and plays an important role for water durability, thermal stability and hardness. Furthermore, we show that the similarity between glass and crystal beyond the nearest neighbour distance is important for glass properties. These results demonstrate that controlling the oxygen coordination and valence of the network-forming cation is necessary for designing the properties of glass. Oxide glass components are basically classified into network formers, network modifiers and intermediates by Zachariasen 1 and Sun 2. Typical network formers satisfy Zachariasen's rules 1 , but V 2 O 5 is classified as a network former 1 or intermediate 3. This is because it is hard for this oxide to form glass on its own because the oxygen coordination number is five in a crystalline phase, which is larger than the coordination number of typical network formers of three and four. V 2 O 5 based glasses have been widely studied for decades because V 2 O 5 glass is a typical semiconducting glass originating from hopping conduction. Indeed, not only fundamental research on electrical properties 4-8 but also applied research on cathode materials for lithium, sodium and magnesium ion batteries have been reported 9-12. This glass also has a low glass transition temperature and relatively low thermal expansion 4. These are quite attractive properties for low-melting glass used for sealing. In this field, lead borate glass with a high percentage of PbO has been applied to sealing below 400 °C in electronic devices, such as IC ceramic packages, crystal oscillators and micro-electro-mechanical systems. Since lead components are a hazardous substance for human health and the environment, it is necessary to avoid the use of PbO, and hence, V 2 O 5 based glass is a promising material for overcoming this problem 13-19. However, there are two critical problems that face the practical application of V 2 O 5 based glass: poor water durability and low thermal stability.

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Section: Discussionmentioning

confidence: 99%

Controlling oxygen coordination and valence of network forming cations

Aoyagi

Kohara

Naito

et al. 2020

Sci Rep

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“…They show that the amorphous oxide consists of entangled polymeric V-0 chains, the structure of which presumably corresponds to the double chains running along the c axis of orthorhombic V~O S .~ Upon hydration, water molecules are adsorbed at the surface of the fibres, destroying their entanglement and giving a more or less viscous geL2 ESR experiments show a drastic modification of the coordination around V"' ions as soon as water molecules are adsorbed, together with the appearance of a Brownian motion of the polymeric chain^.^ Thermal analysis shows that a new hydrated amorphous phase is obtained in which some water appears to be irreversibly linked to the vanadium oxide. 6 This paper presents an IR and Raman study of amorphous V20s at different stages of hydration, from the anhydrous oxide to the colloidal solution. This preliminary study was undertaken in order to obtain more information about vanadium coordination modifications during the hydration process, to characterize the new hydrated species and to study the dynamics of adsorbed water molecules.…”

Section: Introductionmentioning

confidence: 99%

Infrared and Raman study of amorphous V₂O₅

Sánchez

Livage

Lucazeau

1982

J Raman Spectroscopy

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205

118

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Amorphous V205 can be obtained by cooling from the melt. This amorphous oxide is very sensitive to water vapour and can even be dissolved in water to give a vanadium pentoxide gel. The hydration process has been followed by infrared and Raman spectroscopy between 20 and 4000 cm-l. Short-range order in the amorphous oxide appears to be almost the same as in orthorhombic VzOs. The amorphous phase could even be described as made of small crystallites about 100 d in diameter. The structure of amorphous VZO5 does not seem to be modified by water adsorption, at Least during the first stages of the hydration process. However, a drastic modification occurs when enough water is added to give a gel. A general shift to lower frequencies is observed, indicating a weakening of the V -0 bonds, presumably associated with the formation of new V-OH2 bonds. Two different water species have been identified, one of which seems to be almost free of hydrogen bonding. Short-range order in the gels seems to be quite well defined and the spectra could be interpreted either in terms of crystallites, as in amorphous V,O,, or in terms of molecular (or macromolecular) species,containing V205, (H20), groups.

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“…Large quantities of these gels are prepared at present for industrial purposes [3]. Also, polymer-like V2O5×nH2O can be prepared by hydration of amorphous V2O5 under controlled water vapor pressure [5].…”

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confidence: 99%

Vanadium Oxide Gel Films: Optical and Electrical Properties, Internal Electrochromism and Effect of Doping

Kazakova¹,

Berezina²,

Kirienko³

et al. 2014

Journal on Selected Topics in Nano Electronics and Computing

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-The sol-gel science and technology demonstrate an intense development over past few decades accompanied by important applications in electronics. The sol-gel technology represents a typical example of nanotechnology, since the gel products are actually nanocomposites or may contain nanoparticles. That is why the sol-gel science plays a crucial role in the R&D of contemporary nanotechnology for the fabrication of novel materials with new functional properties. In this paper we present an overview of our previous results on the properties of vanadium oxide gel structures, as well as report some recent findings in this area. Electrical and optical (including electrochromic effect) properties, influence of doping with tungsten and hydrogen, electrical switching. Moreover, the properties of vanadium oxide micro-and nanofibers are systematically described and discussed. Applied potentialities of the described phenomena for micro-and optoelectronics (electrochromic devices, sensors, electronic switches, etc) are also discussed.Index Terms -Transition metal oxides, sol-gel, vanadium oxide, metal-insulator transition, electrochromic effect. 1

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A new vanadium pentoxide amorphous phase

Cited by 24 publications

References 13 publications

Controlling oxygen coordination and valence of network forming cations

Controlling oxygen coordination and valence of network forming cations

Infrared and Raman study of amorphous V₂O₅

Vanadium Oxide Gel Films: Optical and Electrical Properties, Internal Electrochromism and Effect of Doping

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A new vanadium pentoxide amorphous phase

Cited by 24 publications

References 13 publications

Controlling oxygen coordination and valence of network forming cations

Controlling oxygen coordination and valence of network forming cations

Infrared and Raman study of amorphous V2O5

Vanadium Oxide Gel Films: Optical and Electrical Properties, Internal Electrochromism and Effect of Doping

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Infrared and Raman study of amorphous V₂O₅