Infrared and Raman study of amorphous V₂O₅

Abstract

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.

Oxidation of vanadium metal in oxygen plasma and their characterizations

“…There are two additional peaks at 1625 and 1460 cm −1 in all samples, confirmed the presence of water molecules on the V surface corresponding to the bending mode of hydroxyl group (-OH). 20,22 All the observed IR results are in consonance with the Raman and XRD analysis. …”

Modification of the Properties of Vanadium Oxide Thin Films by Plasma-Immersion Ion Implantation

“…The spectra of the samples (Figure 8) are qualitatively similar to the data on Raman scattering of vanadium pentoxide reported in the literature [21][22][23]. A peak at 932 cm −1 corresponding to the V 4+ =O bonds is reported in the work [23], and it is not observed in our samples.…”

Mixed conductivity of glasses in the P2O5-V2O5-Na2O system

“…The optical phonon frequency, Vp, evaluated from infra-red and Raman absorption of amorphous V205 between 800 cm -1 to 150 cm ~ [17] is comparable to Vo. Since the vanadium concentration in the pure vanadate glass equals to that of sodium ions in the pure ionic glass, the vanadium-vanadium distance is expected to be quite similar to sodium-sodium distance and the electronic pre-exponential factor, not taking into account the orbitals overlapping contribution should be of the same order of magnitude than that of ionic one.…”