Papers by Author: Nenad Radić

Abstract: In the present work, the surface properties of various Al oxide films were investigated. The oxide films were produced on a stainless steel by spray pyrolysis and cathodic deposition methods. The films obtained represent typical layers that can be used as a support in model systems to investigate alumina-based catalysts. Information about the chemical environment of the Al and O ions in the oxide films depending on the preparation conditions has been deduced from the binding energies of the Al 2p and O 1s electron core levels and corresponding Auger parameters.

Abstract: We have investigated the deposition of ZrO2 and Al2O3 films on a stainless steel (SS) substrate by spray pyrolysis method. The ZrO2 films were deposited from aqueous solution of zirconium dinitrate oxide. For Al2O3 films, a boehmite sol was used. The specific surface areas of samples were determined by the BET-method and sample surfaces were characterized by scanning electron microscopy and X-ray photoelectron spectroscopy. The spray pyrolysis method permits the preparation of ZrO2 and Al2O3 thin films on SS with good adhesion. This method enables preparation of oxide layers with relatively high specific surface area, suitable for applications as catalysts supports.

Abstract: In this paper the adsorption and oxidation of CO on nanocrystalline Au/γ-Fe2O3, Au/α- Fe2O3, γ-Fe2O3 and a series of mixed ferrite with MnxZn1-xFe2O4 composition are investigated. The catalysts were prepared by co-precipitation method and characterized using X-ray diffraction (XRPD), specific surface (BET), transition electron spectroscopy (TEM) and magnetization measurements. A temperature programmed desorption (TPD) study of the water and CO interaction with nanocrystalline adsorbents is presented. The catalytic activities towards CO oxidation increased in the following order: γ-Fe2O3 < MnxZn1-xFe2O4 < Au/γ-Fe2O3 .

Abstract: The structure of thin films of tungsten-carbon, deposited onto monocrystalline silicon substrates by reactive magnetron sputtering (argon + benzene) in a wide range of preparation parameters has been investigated by GISAXS. Substrates were in a fixed position relative to the two adjacent cylindrical magnetrons. Benzene partial pressure was varied from 1% to 10% of the total working gas pressure. A series of samples were prepared, with the substrate held at room temperature and 400°C, and the substrate potential held at floating potential or biased -70 V with respect to the discharge plasma. The bulk particle contribution to the scattering was investigated outside of the specular plane, applying a two dimensional CCD detector. For higher values of benzene partial pressure, the generated films consist of densely packed tungsten carbide grains in an amorphous, carbon rich matrix, while, in some cases, the lower benzene pressure resulted in isolated carbon rich particles in tungsten carbide. From earlier work it is known that the preparation parameters influence the film’s chemical composition, the relatively complex dependence of particle sizes on benzene partial pressure can be explained as a function of the relative carbon content.