Structure and properties of amorphous V<sub>2</sub>O<sub>5</sub>

Nabavi, Majid; Sánchez, Clément; Livage, Jacques

doi:10.1080/13642819108205549

Cited by 82 publications

(54 citation statements)

References 41 publications

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“…This is in contrast to studies suggesting that the vanadate glasses behave as a conventional network former in which only unaffected VO 5 groups are present [20]. Even in the case of pure V 2 O 5 glass it has been reported [21][22] that V 5+ ions exhibit both fourfold and fivefold coordination states depending upon the sample preparation conditions. Thus the structure of the vanadate glasses may not only be dependent on the network modifier but also on the nature of vanadate network itself.…”

Section: Introductioncontrasting

confidence: 59%

X-ray photoelectron spectroscopy (XPS) and magnetic susceptibility studies of vanadium phosphate glasses

Khattak

Mekki

Wenger

2009

Journal of Non-Crystalline Solids

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a b s t r a c tVanadium phosphate glasses with the nominal chemical composition [(V 2 O 5 ) x (P 2 O 5 ) 1Àx ], where x = 0.30, 0.40, 0.50, and 0.60, have been prepared and investigated by X-ray photoelectron spectroscopy (XPS) and magnetization measurements. Asymmetries found in the O 1s, P 2p, and V 2p core level spectra indicate the presence of primarily P-O-P, P-O-V, and V-O-V structural bonds, a spin-orbit splitting of the P 2p core level, and more than one valence state of V ions being present. The magnetic susceptibility data for these glasses follow a Curie-Weiss behavior which also indicates the presence of some V ions existing in a magnetic state, i.e., a valence state other than that of the non-magnetic V 5+ . From qualitative comparisons of the abundance of the bridging oxygen or P-O-P sites as determined from the areas under the various O 1s peaks with the abundances of differing phosphate structural groups associated with the presence of different valence states of the vanadium ions, a glass structure model consisting of a mixture of vanadate phosphate phases is proposed for these glass samples. These include V 2 O 5 , VOPO 4 , (VO) 2 P 2 O 7 , VO(PO 3 ), and V(PO 3 ) 3 with the abundance of orthophosphate (PO 4 ) 3À units increasing with increasing vanadium content.

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Section: Introductioncontrasting

confidence: 59%

X-ray photoelectron spectroscopy (XPS) and magnetic susceptibility studies of vanadium phosphate glasses

Khattak

Mekki

Wenger

2009

Journal of Non-Crystalline Solids

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“…The presence of the FT peak "C" at 2.70 Å is assigned to a vanadium ion from the second shell, 21 and it can be also attributed to the presence of water molecules coordinated with the metallic ion in the axial direction. 1,42 However, the contribution of this oxygen is smaller than that of the vanadium ion (second shell) due to atomic weight, producing a small back-scattering amplitude. 43 It is noted a new length of the V=O bond (1.67 Å), the V-O bonds (not well defined) and V-V interaction (2.61 Å) for x = 1.3.…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

“…The atomic ordering structure can be quite different for the different charge states, and this introduces some uncertainty in the comparison of FT magnitudes, particularly for quantitative correlations of the position and intensity of the peaks with the bond distance and the coordination number. Despite these limitations, this approach has been employed in several publications, 21,[42][43][44] with quite reasonable qualitative results.541 Electrochemical Behavior and Structural Changes of V 2 O 5 XerogelIn Figure 7 (for x = 0), the nearest vanadium neighbour is represented by the peak "A" at 1.60 Å, which is assigned to the V=O coordination shell. The peak "B" at 2.07 Å is associated to the V-O bonds in the distorted square pyramid planar base.…”

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confidence: 99%

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Electrochemical behavior and structural changes of V2O5 xerogel

Huguenin

Torresi

2003

J. Braz. Chem. Soc.

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Filmes finos obtidos a partir de xerogel de V 2 O 5 com distintas quantidades de Li + intercalado eletroquimicamente foram caracterizados utilizando diferentes técnicas in-situ. As mudanças nas propriedades mecânicas foram investigadas utilizando medidas de impedância eletroacústica e estes experimentos indicaram que o processo de intercalação não produz mudanças importantes nas propriedades viscoelásticas do filme; portanto, a equação de Sauerbrey foi utilizada para transformas mudanças de freqüência em mudança de massa. A técnica de microbalança eletroquímica a cristal de quartzo permitiu mostrar a participação do solvente (carbonato de propileno) durante os ciclos de carga/ descarga. Diferentes experimentos espectroeletroquímicos permitiram mostrar a influencia das modificações estruturais no processo de eletro-intercalação. Aa mudanças para uma estrutura mais amorfa do material durante o processo de descarga produz uma diminuição na velocidade dos portadores de carga. A simetria local do vanádio no óxido foi estudada utilizando absorção de raios X.Thin films of V 2 O 5 xerogel were characterized by several in-situ techniques for different amount of intercalated Li + . Changes in the V 2 O 5 mechanical properties were analyzed by electroacoustic impedance data, indicating that lithium intercalation does not produce an important change in the viscoelastic properties. So that, it is possible to use the electrochemical quartz crystal microbalance to measure mass change. Electrogravimetric results showed a significant participation of propylene carbonate molecules during charge/discharge cycles, associated with a significant expansion/ contraction of the structure. The ultraviolet-visible spectrophotometry, chronoamperometry and electrochemical impedance spectroscopy data showed the influence of structural modifications on electronic and ionic properties during the intercalation process. The amorphization of the material in the discharged state produces a diminution in the charge carrier rate. Besides this, changes in the local symmetry of the vanadium ion by extended X-ray absorption fine structure experiments, were verified. Keywords: V 2 O 5 , xerogel, EQCM, lithium intercalation, XAS IntroductionSol-gel process became an usual method for preparing inorganic matrices, which allows the intercalation of different kinds of chemical species. This preparation method is based on reactions of alkoxide hydrolysis and condensation that can start from inorganic salts or organometallic compounds. V 2 O 5 matrix has been widely studied due to its properties, such as being an important semiconductor whose electronic conductivity is associated to the electronic jump between V 5+ and V 4+ ions. 1 V 2 O 5 xerogels have been used as host materials for several metal cations 2 and they are also studied as cathodes for secondary lithium batteries.3,4 The lamellar structure allows Li + intercalation/deintercalation during the reduction/ oxidation of vanadium cations. 5 This transition metal oxide also gives optically transparent t...

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“…Diamond-anvil cell based Raman and X-ray diffraction measurements have revealed only the α-β transition occurring around 6-7 GPa [28,29]. It may also be pointed out that in V 2 O 5 a glassy/ amorphous state, formed by splat-cooling [30] (bulk) and physical vapor deposition [31] The pattern labelled R-53 is that of the recovered sample at ambient pressure after subjecting it to 53 GPa.…”

Section: Resultsmentioning

confidence: 99%

Polyamorphism in network structures

Arora

2012

J. Phys.: Conf. Ser.

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Abstract. Reports of high-density amorphous forms of ice, quartz and Si have intensified the search for amorphous polymorphs in other systems. The network structures that exhibit pressure-induced amorphization are interesting from the point of view of polyamorphism. Recent in-situ high pressure Raman scattering and synchrotron x-ray diffraction studies on negative thermal expansion material zirconium tungstate have revealed an amorphous to amorphous transition at 19 GPa. The transition was identified for the discontinuities in the structural parameters such as position and height of the first peak of the structure factor and that in the tungstate internal vibrational mode frequency. Another compound, vanadium pentaoxide that forms a glass during melt-quenching, is also found to turn amorphous at 40 GPa, pointing to a possibility of polyamorphism.

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Structure and properties of amorphous V₂O₅

Cited by 82 publications

References 41 publications

X-ray photoelectron spectroscopy (XPS) and magnetic susceptibility studies of vanadium phosphate glasses

X-ray photoelectron spectroscopy (XPS) and magnetic susceptibility studies of vanadium phosphate glasses

Electrochemical behavior and structural changes of V2O5 xerogel

Polyamorphism in network structures

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Structure and properties of amorphous V2O5

Cited by 82 publications

References 41 publications

X-ray photoelectron spectroscopy (XPS) and magnetic susceptibility studies of vanadium phosphate glasses

X-ray photoelectron spectroscopy (XPS) and magnetic susceptibility studies of vanadium phosphate glasses

Electrochemical behavior and structural changes of V2O5 xerogel

Polyamorphism in network structures

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Structure and properties of amorphous V₂O₅