Persons

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A series of studies for explaining the role of superexchange interactions in formation of the ferromagnetic state of cobaltites of LaSrCoMe O(Me = Cr, Ga, Fe) systems and LaSrMnMO (M - Nb, Mg) manganites with the perovskite structure have been performed. The obtained results have testified that ferromagnetism in cobaltites can be realized within the homovalent state of the cobalt ions. The initial compound ( x = 0) is a ferromagnetic ( T =247 K) with the saturation magnetization close to 2µB (at T = 30 K) per formula unit (at T = 30 K). It has been shown that the chemical substitution of cobalt for chromium ones decreases the spontaneous magnetization down to 0.3µB (at x = 0.2), while the substitution of cobalt for iron ions ( x = 0.2) does not modify the magnetization. The obtained data are interpreted in the model of positive superexchange interactions between cobalt and iron and the negative ones between cobalt and chrome. It has been demonstrated that LaSrMnNbO is ferromagnetic ( T = 145 K) with magnetic moment 3.1 µ/Mn at 10 K. No evidence of cooperative orbital ordering in manganite compounds has been revealed. Partial chemical substitution of Nb ions for Mg ones leads to formation of Mn ions, while it does not improve the ferromagnetic state. The intensification of structural distortions diminishes the ferromagnetic component. It has been assumed that the ferromagnetic state is caused by significant hybridization of ėg orbitals of manganese and oxygen ions thus strengthening the positive component of superexchange interactions.

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Using the method of successive ionic-layer adsorption from water solutions of different composition, the InS films on the surface of TiO and porous anodic AlO have been formed. It has been found that the composition of cationic and anionic solutions-precursors affect the optical band gap of the films, which varies within the 1.97-2.65 eV range, that is explained from positions of the oxygen content change in InS. The discovered dependencies of optical properties on the pH value of anionic precursors and the anion nature in the cationic precursors well agree with the calculated conditions of chemical equilibrium in the investigated systems. The efficiency dependence of the photo electrical transformation of solar elements with the extremely thin absorbing layers on the oxygen content in the InS films, produced by successive ionic-layer adsorption, has been demonstrated.

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The peculiarities in kinetics of the local probe oxidation of ultra thin V, Nb, Ta, Ti, TiN, TiN, W metal films have been investigated. It has been found that the process kinetics is determined by such properties of the material being oxidized, as the specific resistance, presence of the surface natural oxide film and its thickness, the correlation of specific density of metal and oxide, the oxidation process electric-chemical constant. As a material, providing the maximum productivity in formation of the local dielectric regions, having nanometer dimensions, vanadium has been chosen, that is characterized by maximum rate of the anodic probe oxidation.

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The information about the process of forming thin titanium oxide films by pulling out the substrates from the titanium tetraisoproproxide alcohol solution has been presented. It has been shown that the deposited titanium oxide contains a continuous film and the globules of titanium oxide formed on its surface. It has been revealed that the density and the height of the globules depend on the rate of pulling out the substrate from the solution and the relative humidity in the chamber, and the thickness of the continuous film of titanium oxide is a relatively constant value.

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The influence of the porous alumina geometry on the properties of the humidity sensitive composites (Al - AlO - Ti) has been studied. The basic stages of the capacitive sensor active layer manufacturing have been reported. The structure relative capacitance has been shown to depend mainly on the pore diameter and the humidity value.

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The mechanism of the alkali metal leakage at the glass-ceramic junction of sapphire-niobium has been analyzed. The physical fundamentals of leakage monitoring of alkali metal based on the radiation intensity of the resonance lines have been considered and a thermodynamic evaluation of the reliability of the glass-ceramic junctions has been performed. Based on the developed method the decrease dependence in the rubidium resonance lines intensity over the life of the high-frequency low-pressure cells has been obtained and the recommendations how practically to apply the proposed method and the obtained have been provided.

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The urgency of creating a math model of the amalgam components evaporation in discharge radiation sources (lamps) is determined by dependence of the special purpose discharge source radiation parameters on the irradiative additive vapor pressure, which depends on the dimensions and temperatures of discharge, cathode and anode volumes. In connection with a variety of discharge lamps constructions, a system of equations, allowing determining the amalgam components pressure, considering the specific design and the temperature profile of a discharge tube, has been presented in this work. The infrared radiation source design of the aircraft protection system has been described in detail. The effect of the amalgam mass and composition upon the pressure of the irradiative additive at fixed dimensions and temperatures of the discharge, cathode and anode volumes has been revealed. As a result of the performed calculations the dependences of cesium and mercury pressure versus the discharge tube cold point temperature have been obtained. The cesium pressure growth peculiarities at the discharge transmission from saturated vapors to unsaturated ones have been clarified.

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Some features of the 3D silicon structures formation by locally formation of porous silicon as a sacrificial layer have been studied. It has been formed by metal-assisted chemical etching of a single crystal wafer of Si with silver films (50 and 100 nm) as a catalyst. The influence of ionic Ag mass transfer, caused by the temperature gradient, on the surface morphology of the formed structure according to the linear size of the mask-catalyst has been determined.

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The formation of nanostructures by the method of the chemical precipitation from the gas phase using PECVD and glow-discharge plasma has been considered. The investigations were carried out in the 3000 - 700 °C temperature range. The influence of the Ni catalyst thickness and of the concentration of the carbon-containing components in vapor phase on the carbonic deposit structure has been studied. The productive growth of the homogeneous vertical nanotubes and grapheme flakes at 350 °C has been obtained. The electrophysical features of the obtained structures have been studied.

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The results of the investigated sensory properties of the zinc oxide films (ZnO), obtained by the sol-gel technology, have been presented. It has been shown that the variation of the films resistance during the repeated thermal cycling is in the temperature range of 50 - 500 °C, under conditions of the different relative humidity it is (7.5 - 90%) when exposed to the nitrogen oxides (NO and NO).

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