Structural properties of the epitaxial (SiC)1 − x (AlN) x solid solution films fabricated by magnetron sputtering of SiC-Al composite targets

Epitaxial layers of the (SiC)_{1 ? x} (AlN) _x solid solution with x ≈ 0.12 and x = 0.64 without macroscopic structural distortions were grown using a new technique. It was established that the compositional dependences of crystal lattice parameters of the epitaxial films obey the Vegard’s law with an error of ～0.03. This confirms that there is formation of isomorphic substitutional solid solutions in the SiC-AlN system.     

Derivatographic studies of a nanocomposite based on polypropylene and DK1 nanogel

Derivatograms of a polypropylene (PP) composite containing 2, 4, and 10 vol % of D_K1 are represented. Regardless of the crystallization method, all the D_K1 materials under study undergo a thermal oxidative breakdown at 305–320°C. An increase in the volume content of D_K1 from 4 to 10% leads to a shift of the depolymerization temperature to higher values, which is most probably attributed to the formation of crosslinked structures in the material. Owing to this, after heating to 500°C, the amount of the solid residue in the PP + 10 vol % D_K1 material crystallized by rapid cooling achieves 62%.     

Preparation of high-octane oxygenate fuel components from plant-derived polyols

The ketalization of polyols (glycerol, xylitol, xylose) in the presence of a number of heterogeneous acid catalysts has been studied. It has been shown that zeolite catalysts exhibit high activity in the formation of the acetone ketal of glucose in a flow system with the quantitative selectivity for the 1,2-product. The best catalyst is zeolite beta; in the presence of this zeolite and excess acetone, the yield is over 90% or, in the case of the structured reactor, even greater than 98% It has been shown that zeolite-based systems catalyze the formation of ketals of xylitol and xylose with a yield of up to 50% in the presence of excess acetone.     

Multiferroic behavior of the functionalized surface of a flexible substrate by deposition of Bi2O3 and Fe2O3

Thin films of bismuth and iron oxides were obtained by atomic layer deposition (ALD) on the surface of a flexible substrate poly(4,4′-oxydiphenylene-pyromellitimide) (Kapton) at a temperature of 250°C. The layer thickness was 50 nm. The samples were examined by secondary-ion mass spectrometry, and uniform distribution of elements in the film layer was observed. Surface morphology, electrical polarization, and mechanical properties were investigated by atomic force microscope, piezoelectric force microscopy, and force modulation microscopy. The values of current in the near-surface layer varied in the range of ±80 pA when a potential of 5 V was applied. Chemical analysis was performed by X-ray photoelectron spectroscopy, where the formation of Bi₂O₃ and Fe₂O₃ phases, as well as intermediate phases in the Bi–Fe–O system, was observed. Magnetic measurements were carried out by a vibrating sample magnetometer that showed a ferromagnetic response. The low-temperature method of functionalization of the Kapton surface with bismuth and iron oxides will make it possible to adapt the Bi–Fe–O system to flexible electronics.     

Magnetoresistance effect in PP + Fe based nanocomposite system

The article investigates the acqusition, structure, magnetic properties and magnetoresistance effect of nanocomposites on the basis of polypropylene matrix and iron nanoparticles, structure, magnetic properties and magnetoresistance. AFM results illustrate that the increase in the volume content of Fe nanoparticles in the polymer matrix causes changes on its supramolecular structure. As a result of the MFM studies, it has been defined that, nanoparticles dispersed in the polymer matrix form domains in the local areas and the sizes of domains vary from 150 to 400?nm. The study of magnetic properties of PP?+?Fe based nanocomposites showed that intrinsic magnetization increases with increasing magnetic field intensity and saturation occurs at certain value of intensity. If the field is reduced, remanent magnetization and hysterezis loop is observed. The dependence of PP?+?Fe based nanocomposites on the magnetic field was investigated and magnetoresistive effect was observed and it was found to be related with the presence of tunneling magnetoresistance effect in these nanocomposites.     

Prospects of development of highly mineralized high-temperature resources of the Tarumovskoye geothermal field

The promising nature of integrated processing of high-temperature geothermal brines of the Tarumovskoye geothermal field is shown. Thermal energy of a geothermal brine can be converted to the electric power at a binary geothermal power plant (GPP) based on low-boiling working substance. The thermodynamic Rankine cycles are considered which are implemented in the GPP secondary loop at different evaporation temperatures of the working substance―isobutane. Among them, the most efficient cycle from the standpoint of attaining a maximum power is the supercritical one which is close to the so-called triangular cycle with an evaporation pressure of р_e = 5.0 MPa. The used low-temperature brine is supplied from the GPP to a chemical plant, where main chemical components (lithium carbonate, burnt magnesia, calcium carbonate, and sodium chloride) are extracted from it according to the developed technology of comprehensive utilization of geothermal brines of chloride-sodium type. The waste water is delivered to the geotechnological complex and other consumers. For producing valuable inorganic materials, the electric power generated at the GPP is used. Owing to this, the total self-sufficiency of production and independence from external conditions is achieved. The advantages of the proposed geotechnological complex are the full utilization of the heat potential and the extraction of main chemical components of multiparameter geothermal resources. In this case, there is no need for reverse pumping, which eliminates the significant capital costs for building injection wells and a pumping station and the operating costs for their service. A characteristic of the modern state of the field and estimated figures of the integrated processing of high-temperature brines of well no. 6 are given, from which it follows that the proposed technology has a high efficiency. The comprehensive development of the field resources will make it possible to improve the economic structure of the region and fully meet the needs of Russia in lithium carbonate and sodium chloride.     

The study of deuterium permeability of film-forming inhibitors with the addition of fullerenes

In this work, the results of the hydrogen permeability study of a composite film-forming inhibitor are considered. Film-forming inhibitor consists of polyether urethane and synthesized fullerenes C60 and C70 in pure form. Two types of samples were used: uncoated and coated stainless steels with composite polyether urethane/fullerene varnish. The experimental work was based on the study of the dependence of the permeation reduction factor on the temperature in the reactor. For the coated sample, the minimum temperature was 623 K at which the deuterium flux was registered. Here we assume that at temperatures below 573 K the output pressure caused by the deuterium flow through the sample is less than 10^?10 Pa. The rate of steady-state flow through a coated sample is significantly lower than for an uncoated one at temperatures 573–673 K. The deuterium penetration rates through the two samples increase and reach similar stationary values starting at 723 K.     

Sorption of Uranium on Zirconium Phosphate Inorganic Cation Exchanger

Uranium sorption on the zirconium phosphate inorganic cation exchanger is studied. Zirconium phosphate (ZP) efficiently sorbs uranium from nitric acid solutions over the pH range 3.0-5.0. The uranium distribution coefficients decrease in the presence of nitrates of alkali and alkaline-earth metals. The kinetics of static desorption of uranium with HNO₃ and also of its dynamic sorption and desorption are studied. The mechanism of U sorption on ZP is analyzed. The exchange rate of the hydrogen ions in the sorbent phase for uranyl ion is controlled by the gel kinetics, and the rate-determining stage is the inner diffusion of uranium in the sorbent grain. The kinetic parameters of this exchange are determined. The sorption rate doubles with increasing temperature from 20 to 40°C and pH from 3.0 to 5.0.