Advanced Materials Research Vol. 1085

Abstract: Formation of triplet states in aqueous herbicide solutions excited by nanosecond radiation of 4^th harmonic of Nd:YAG laser (wavelength 266 nm) is revealed by the pump-probe method. During photosensitized 8-MOP oxidation of herbicides, formation of triplet states of the photosensitizer and of the hydrated electron is observed in the process of two-step photoionization of 8-MOP.

Abstract: Soda lakes located close to uranium deposits of West Mongolia contain elevated concentrations of uranium, reaching, in some cases, 1 to 3 mg/l. The concentration of uranium in the lakes of Russian Altai is lower and varies from 0.001 to 0.03 mg/l. The greatest uranium resources (about 6000 tons) are stored in Hyargas Nuur Lake, Western Mongolia. In addition to uranium and salts of sodium and magnesium increased contents of boron (up to 250 mg/l), bromine (up to 1.1 g/l), lithium (up to 600 mg/l), strontium (up to 8 mg/l) were determined in the lake waters. A scheme for complex processing of uranium-bearing lake waters, the first stage of which includes extraction of uranium using iron-containing sorbents or anion exchange resins is considered. Uranium compounds, bromine, iodine, boron, lithium and other elements found in salt lakes are an important raw material base for the production of advanced materials.

Abstract: This article is devoted to investigation of the synthesis process of exfoliated graphite. Exfoliated graphite was obtained from graphite oxide using thermal exfoliation. Graphite oxide samples were synthesized using modified Hummers method. The influence of the synthesis process parameters such as heating rate, temperature, exposure time on the properties of graphite oxide were investigated. The as-received exfoliated graphite were tested as electrode for supercapacitors. The capacitance of the supercapacitors based on exfoliated graphite varied in a range of 17-129 F/g.

Abstract: In this work, we have synthesized homogeneous, ordered CdSe and CdSe/ZnS core/shell quantum dots (QDs) by chemical route and characterized them using X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS), and Photoluminescence (PL) spectroscopy. Coating with shell material was confirmed by red shift as well as enhancement in the PL peak compared to bare QDs. DLS data showed QDs and core/shell to be stable. PL spectra are red shifted relative to the excitation wavelength. Bare QDs and the core/shell material shows a Stoke-shift of 16 and 18 meV respectively.

Abstract: The special features of nanoparticles formation by laser ablation of volume metallic zinc targets in various solvents using sulfur precursors are studied. Semiconductor cadmium sulphide nanoparticles with average sizes 10–15 nm are synthesized by zinc ablation in the presence of hydrogen sulfide and thioacetamide, and their composition, structure, and optical properties are investigated. It is established that with the use of H₂S, only CdS particles are formed in the medium.

Abstract: The article demonstrates how time and speed of pressure growth in the course of microwave-hydrothermal processing affect surface morphology and photocatalytic activity of tin (II) oxide. The experiment proved that the materials’ pore size and pore volume influenced their sorption activity and the speed of photocatalytic degradation of methyl orange.

Abstract: The alloying of the titanium layer by yttrium is carried out with the combined method of electroexplosive alloying and the subsequent radiation by a high-intensity electron beam. The research of structure, element and phase composition, mechanical and tribological properties of the alloyed layer is executed. The saturation of the titanium layer by atoms of yttrium, oxygen and carbon that leads to formation of oxides and carbides of the titanium and yttrium is revealed. The formation of two types of an eutectic is established. It is shown that the eutectic enriched with the titanium has a globular form when the eutectic enriched with yttrium has a plated one. The multiple increasing of microhardness, decreasing of friction coefficient and the wear rate of the alloyed layer is revealed.

Abstract: Phase composition and structure of boron carbide powder with dispersion of particles varying from 30 nanometers to 0.8 micrometers were investigated by the methods of X-ray diffraction, scanning and transmission electron diffraction microscopy. It was obtained bimodal powder mixtures with relatively quasi-uniform distribution of nanosized powder particles.

Abstract: Change of the wear resistance of a copper couple under friction during nitrogen ion implantation was investigated using tribological tests in argon atmosphere. The structural-phase state of the treated sample surface was investigated by TEM, the microhardness was determined using nanoindenter, the penetration depth of nitrogen ions was investigated by the secondary ion mass spectrometry. It was established that the high nitrogen fluencies under ion implantation increase wear resistance of a copper friction pair 1.5-4.5 times as well as the microhardness of the sample surface.

Abstract: Series of Pd-Ag/SiO₂, Pd/CeO₂ and Pd-Ag/CeO₂ catalysts with different Pd/Ag ration were synthesized and investigated. It was shown that simultaneous reduction of Pd and Ag took place for Pd-Ag/SiO₂ and Pd Ag/CeO₂ catalysts during TPR-H₂. That may be associated with formation of bimetallic Pd-Ag particles. The high temperature of Pd reduction was observed for Pd/CeO₂ and Pd-Ag/CeO₂ catalysts. That was associated with strong interaction of PdO with CeO₂ or formation of mixed Pd_xCeO_2-δ phase.