Papers by Author: G.E. Yalovega

Abstract: The cobalt-containing polyacrylonitrile (PAN) films were fabricated using IR-pyrolysis under low vacuum conditions. It was found that Co/PAN films have a porous structure and cobalt nanoparticles with size 0.1-0.2 μm embedded into PAN matrix. Besides, as a result of interaction between PAN matrix and Co ions unsaturation in the polymer backbone is observed caused by the transformation of the C≡N triple bond to a C=N double bond. At the same time formation of Co-N bond is observed.

Abstract: Morphology, atomic and electronic structure of CuOx/CNT nanocomposite synthesized by electrochemical method were investigated using methods scanning electron microscopy (SEM), X-ray absorption spectroscopy (XANES and NEXAFS) and X-ray photoelectron spectroscopy (XPS). It has been shown that by the formation of a nanocomposite changes in morphology, oxidation state and phase composition of CuOx nanoparticles in comparison with the initial particles were observed. The initial oxidation of carbon nanotube (CNT) surface leads to reduction ability of the formation of chemical bonds between the nanoparticles and tubes.

Abstract: In the paper the SiO₂CuO_x and SiO₂(CuO_xSnO_y) thin films were deposited from the alcoholic solutions employing the sol-gel technique. The films were characterized by means of SEM (scanning electron microscopy) and 2p x-ray photoelectron spectroscopy (XPS). The SEM studies found the grain shape changes from flower-like to regular shaped inorganic agglomerates as result of adding the SnCl₄ into the sol. The X-ray photoelectron spectroscopy (XPS) studies showed the presence both CuO and CuO₂ phases and formation of a double CuSiO₃ oxide phase.

Abstract: Thin SiO₂ZrO₂ films were prepared, up to 0.2 μm thick, by means of the sol–gel technology and characterized by a Scanning electron microscopy and X-ray diffraction. It is shown the presence of monoclinic, cubic and tetragonal phases of ZrO₂ in the SiO₂ matrix. The crystallites sizes depend on the annealing temperature of the film and amount to 35 and 56 nm for the films annealed at 773 and 973 K, respectively. The films resistance is rather sensitive to the presence of NO₂ and O₃ impurity in air at lower operating temperatures in the range of 30-60°C.

Abstract: SiO_xCuO_y thin films were prepared by the deposition on to the Si/SiO₂ substrates from the alcoholic solutions employing the sol-gel technique. The various analytic techniques were applied to characterize structure and properties of the films under study . The both X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) studies showed the presence CuO as well as CuO₂ phases and formation of a dual-oxide CuSiO₃ with the average crystallites sizes of 35-50 nm. The conductance of the films was rather sensitive to the presence of 1-20 ppm NO₂ concentration at the operating temperatures in the range of 20–200 ^◦C.