Papers by vladimiras bondarenka
Lithuanian Journal of Physics, 2008
Vanadium pentoxide xerogels were prepared by using sol-gel technology. As-prepared samples of xer... more Vanadium pentoxide xerogels were prepared by using sol-gel technology. As-prepared samples of xerogels were heated up to 580 K in order to remove the bonded water. The chemical composition of xerogel samples and thin films has been studied by X-ray photoelectron spectroscopy (XPS). XPS data have shown that pure V2O5 compound was formed. After thermal treatment, in the XPS spectra the main changes occurred in the vicinity of the O 1s peak due to the removal of water from xerogel. The optical properties of V2O5 films were studied by optical transmission and spectroscopic ellipsometry. Ellipsometric measurements have been carried out in the spectral range of 0.5-5.0 eV at 300 K. The changes in the optical spectra were observed after thermal annealing of as-prepared xerogel samples. The obtained data have shown that thermal treatment of V2O5 thin films has strongly influenced the optical transitions involving both localized and higher-lying conduction bands.
The X-ray photoelectron spectroscopy (XPS) was performed to study surface and volume composition,... more The X-ray photoelectron spectroscopy (XPS) was performed to study surface and volume composition, valence states and the concentration of hydroxyl groups in epitaxial LaNiO 3-x thin films after aging in air. The existence of at least few different forms of oxygen as lattice oxide, hydroxyl groups and adsorbed water in the samples is shown by XPS characterization. The lanthanum and nickel exist in oxide and hydroxide chemical states. The concentration of hydroxyl groups increases at the surface but it is distributed through the volume as well. It was found that the surface Ni/La concentration ratio is close to the stoichiometric bulk value.
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Papers by vladimiras bondarenka