Unconventional magnetism of non-uniform distribution of Co in TiO2 nanoparticles

High-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) analysis, electron paramagnetic resonance (EPR), X-ray absorption spectroscopy (XAS), magnetic methods, and density-functional theory (DFT) calculations were applied for the investigations of Co-doped anatase TiO2 nanoparticles (∼20 nm). It was found that high-spin Co2+ ions prefer to occupy the interstitial positions in the TiO2 lattice which are the most energetically favourable in compare to the substitutional those. A quantum mechanical model which operates mainly on two types of Co2+ – Co2+ dimers with different negative exchange interactions and the non-interacting paramagnetic Co2+ ions provides a satisfactorily description of magnetic properties for the TiO2:Co system. © 2020 Elsevier B.V.Russian Foundation for Basic Research. Ministry of Science and Higher Education of the Russian Federatio

Carbon States in Carbon-Encapsulated Nickel Nanoparticles Studied by Means of X-Ray Absorption, Emission, and Photoelectron Spectroscopies

Electronic structure of nickel nanoparticles encapsulated in carbon was characterized by photoelectron, X-ray absorption, and X-ray emission spectroscopies. Experimental spectra are compared with the density of states calculated in the frame of the density functional theory. The carbon shell of Ni nanoparticles has been found to be multilayer graphene with significant (about 6%) amount of Stone--Wales defects. Results of the experiments evidence protection of the metallic nanoparticles from the environmental degradation by providing a barrier against oxidation at least for two years. Exposure in air for 2 years leads to oxidation only of the carbon shell of Ni@C nanoparticles with coverage of functional groups.Comment: 16 pages, 6 figures, accepted in J. Phys. Chem.

Usage of integral representations for the surface current density when solving the problem on radiation of ultra wideband signals by unenclosed bent shields

The solution of the problem of ultra wideband signal radiation by a TEM-horn is proposed. It is based on the solution of the integral representation for a surface current density and takes into account the Meixner conditions on an edge

АНАЛІЗ ТЕХНІЧНИХ ХАРАКТЕРИСТИК РАДІОЛІНІЙ УПРАВЛІННЯ ВИБУХОВИМИ ПРИСТРОЯМИ

The technical characteristics of radio control explosive devices as frequency range, range, path loss, bandwidth and sensitivity of the receiver analyzed. The numerical values of the characteristics necessary for the effective operation of the link.Проаналізовані технічні характеристики радіоліній управління вибуховими пристроями: частотний діапазон, дальність дії, втрати на трасі, смуга частот і чутливість приймача. Наведені числові значення характеристик, необхідні для ефективної роботи радіолінії