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The catalytic properties of Inerton-supported nickel nanoparticles in benzene hydrogenation have been studied; rate constants of the reaction at different temperatures have been calculated. Activation energy and conversion have been determined, and the effect of size of nickel nanoparticles on their catalytic properties in benzene hydrogenation has been discussed.

We have studied conditions for the synthesis of intermetallic phases in the Cu–Al–Ni system by selective laser sintering/melting, in particular by heating a powder mixture to 300°C. The effects of laser synthesis and heating on the microstructure of the intermetallic phases in the samples obtained have been studied using electron microscopy, optical metallography, and X-ray diffraction analysis. The results demonstrate high sinterability of stoichiometric mixtures. Resistivity measurements indicate that the samples exhibit a shape memory effect. We discuss the feasibility of producing biomicroelectromechanical systems using layerby- layer synthesis.

The mechanical activation (MA) of a charge of a hard magnetic 22Kh15KT alloy is studied by wet and dry milling in a planetary mill in a medium of argon and ethyl alcohol with addition of surface-active materials and without them. It is shown that, upon dry MA, powder alloy components are alloyed with formation of two bcc solid solutions and, upon wet MA, charge particles are only intensely dispersed. Dispersion is developed at the highest degree in the first five minutes of MA.

Spherical zinc particles ranging in average size from 275 to 760 nm and covered with platelike zinc oxide particles on the order of 10 nm in size have been prepared by levitation-jet aerosol synthesis through condensation of zinc vapor in an inert-gas flow. The nanoparticles have been characterized by transmission electron microscopy, X-ray diffraction, BET measurements, and vibrating-sample magnetometry. The results indicate that the observed ferromagnetic ordering is due to changes in unit-cell volume on the surface of the nanoparticles. High-temperature magnetization data demonstrate that the ferromagnetic ordering of the nanoparticles persists up to 750 K.

The relative cross sections of processes taking place when H+ and He2+ ions with an energy of 6z keV (z is the ionic charge) capture an electron from molecules of C5H11NO2S methionine (proteogenic amino acid) and C6H13NO2 norleucine (nonproteogenic amino acid) are measured by time-of-flight mass spectrometry (a methionine molecule transforms into a norleucine molecule by substituting the CH2 group for the S heteroatom). The fragmentation pattern of resulting molecular ions is established from correlation analysis of the detection times of all fragment ions. The results are compared with experimental data for fragmentation of the same molecules ionized by electrons and photons. In these amino acids, the pattern of molecular ion fragmentation is found to depend on the type of molecule ionization. However, the detachment cross section of the COOH neutral group or residue (neutral or charged) R of a side chain of the amino acid is invariably among the largest. The relative cross sections of capture with single and double ionization of molecules are measured.

Pseudospherical copper ferrite particles 20 to 90 nm in average size were prepared by an aerosol method through condensation of iron and copper vapors in an inert-gas flow, followed by the oxidation of the resulting two-phase powder under heterogeneous combustion conditions to an almost single-phase product. The nanoparticles were characterized by scanning electron microscopy, X-ray diffraction, BET measurements, and vibrating-sample magnetometry. Analysis of the X-ray diffraction data and the behavior of the magnetization of reaction intermediates and final synthesis products in the range 400–1100 K made it possible to propose models for the nanostructure of the particles and establish the likely sequence of the observed phase transformations.

Pseudospherical nickel ferrite particles 25 to 70 nm in average size were prepared by a crucibleless aerosol method through cocondensation of Fe and Ni vapors in an inert-gas flow containing a small amount of air. The particles were characterized by transmission electron microscopy, X-ray microanalysis, X-ray diffraction, BET measurements, and vibrating-sample and SQUID magnetometry. The results were used to optimize process parameters for the preparation of particles with a tailored size, specific surface area, and saturation magnetization. A dc electric field applied to the condensation zone can serve to improve the phase purity of nickel ferrite nanoparticles, reduce their size, and change their Curie temperature.

The time-of-flight mass spectrometry method is used to study processes occurring when 36-keV multiply charged Ar ions (Ar6+) capture electrons from adenine and uracyl molecules. Adenine and uracyl constitute one of two base pairs entering into the RNA composition. The fragmentation scheme of resulting molecular ions is derived by analyzing correlations between the detection times of all fragment ions. Fragmentation patterns for molecular ions resulting from molecule ionization by photons, electrons, protons, and multiply charged ions are compared.

Time-of-flight mass spectroscopy methods are employed for studying processes occurring during capture of electrons by 3He2+ and Ar6+ multiply charged ions with energy 6z keV (z is the ion charge) from C2Hn molecules (n = 2, 4, 6) with different multiplicities of C-C bonds. Fragmentation schemes of the molecular ions formed in such processes are established from analysis of correlations of recording times for all fragment ions. The absolute values of the cross sections of capture of an electron and capture with ionization are measured, as well as the cross sections of formation of fragment ions in these processes. The absolute values of total capture cross sections for several electrons are determined.

The behavior of frontally burning heterogeneous systems containing boron, aluminum, gallium, indium, yttrium, lanthanum, and ytterbium is studied by a potentiometric method. These systems are used for self-propagating high-temperature synthesis of some oxide materials. The peak values of the electromotive force of combustion arising between the combustion wave front and the synthesis products in systems with participation of triple-charged ions of these chemical elements are found to be directly proportional to the ionic potential of the chemical element and reach 150–400 mV. The use of two heteropolarly reacting systems as elements of the electromotive force of combustion in one array assembly allows the difference in potentials to be increased to 2.3 V.

Spherical oxidized nickel particles 15 to 200 nm in average size have been produced by a crucibleless aerosol method involving metal vapor condensation in an inert gas flow and oxidation processes. The particles have been characterized by scanning electron microscopy, X-ray microanalysis, X-ray diffraction, BET surface area measurements, and vibrating-sample magnetometry. The process parameters have been optimized for the preparation of particles with tailored size, specific surface area, and saturation magnetization. A dc electric field applied to the condensation zone during the oxidation process reduces the size and increases the extent of oxidation of the particles. We have studied low-temperature oxidation of carbon monoxide and propane on nickel nanopowders differing in particle size and extent of oxidation. The nanoparticles with optimized characteristics have been shown to have a marked catalytic effect on these processes.

The effect of a contactless electric field on the interactions involved in the combustion of the BaO2-Fe and MnO2-Fe systems is studied. The results are indicative of the possibility of increasing the extent of chemical conversion during the combustion of oxide systems by applying an external electric field. A possible mechanism of the influence of an electric field on the redox processes occurring during the combustion of oxide systems composed of a metal fuel and a solid oxidizer is described.

The mutual influence of barium peroxide and sodium perchlorate on thermolysis of the (2 ⎯ x)BaO2-xNaClO4 system (x = 0-2.0) has been studied. It has been demonstrated that the use of the physicochemical mechanism of this influence makes it possible to carry out heterogeneous combustion in complex oxide systems in the controlled regime by changing the mutual concentration of solid inner reaction oxidizers. An explanation of the thermal and kinetic effects in the thermolysis of the peroxide-per� chlorate system has been suggested. Alkali metal chlorates and perchlorates decompose on heating to evolve oxygen. This makes them suitable for using as oxygen sources in oxidation reactions, including the selfpropagating hightemperature syn� thesis (SHS) of complex oxides, which requires the presence of a fuel and oxidizer in the reaction system (1, 2). In the SHS of complex oxide materials, solid inner reaction oxidizers, such as sodium perchlorate NaClO 4 , can be used as an alternative or complement to gaseous oxygen. Sodium perchlorate contains more than 50 wt % of oxygen, which is completely evolved at relatively low temperatures (3). However, in the com� bustion reaction, the time interval of the vigorous oxy� gen evolution from the solid oxidizer may not coincide with the intense exothermic oxidation reaction (com� bustion) of the metal component. If this is the case, the chemical reaction rate significantly decreases, which leads to incomplete reaction of the components and even to combustion failure. The kinetic parame� ters of sodium perchlorate thermolysis can be changed by both external physical actions (for example, electric field (4)) and various chemical additives. As is known, small additions (up to 4 wt %) of some metal oxides catalyze the thermolysis of potassium perchlorate and sodium chlorate (5). Inasmuch as metal oxides are components of reaction mixtures for the SHS of complex oxide materials, if the character of the influence of some oxide on perchlorate is known, it is possible to find the bath composition at which the process will be controllable and will proceed at defi� nite rates and temperatures. In SHS processes, alkali metal and alkaline earth peroxides are often used as oxide components. For example, barium peroxide BaO 2 is used in the synthesis of hightemperature superconducting ceramics (HTSC—YBa2Cu3O 7- x), barium hexaferrite (BaFe12O19), barium stannate (BaSnO 3 ), etc. In these systems, the fuel is a powder of a corresponding metal: iron, copper, and tin. Thus, to determine optimal component ratios when sodium perchlorate is used as a solid inner reaction oxidizer, it is necessary to know the mechanism of the influence of superstoichiometric NaClO4 , as a chemical addi� tive, on the synthesis in these systems. To determine this mechanism, we considered the mutual influence of NaClO4 and BaO2 on thermolysis of these com� pounds in the reaction mixture.

The behavior of frontally burning heterogeneous systems containing chromium, molybdenum, and tungsten, which are used in the self-propagating high-temperature synthesis of complex oxide materials, was studies by the potentiometric method. It was revealed that the peak emf between the combustion wave front and the synthesis products can be as high as 2 V, depending on the chemical composition of the initial stock. A mobile registering probe moving with the velocity of combustion wave propagation makes it possible to substantially increase the time of emf recording

Fullerite with the bulk formula ArxC60, where 0.60 < x < 0.75, was synthesized by precipitation from a mixture of argon-saturated solutions. The fcc unit cell parameter in the sample was 1.422 nm; the orientational phase transition (OPT) temperature was 247 K. These values noticeably differ from the relevant parameters of undoped fullerite (1.416 nm and 260 K, respectively). Heating accompanied by argon evolution restores the fullerite C60 structure.

For fullerite C60 with intercalated oxygen, a sharp (by three orders of magnitude) increase in the intensity of the EPR signal with a g-factor of 2.0024 was observed at ∼200°C. Studies of gases formed in heating of the sample in a vacuum showed that molecular oxygen was largely released at temperatures below 100°C, whereas the gas phase formed as the temperature increased to 200°C contained carbon oxides CO and CO2 in addition to oxygen. The conclusion was drawn that the intensity of the EPR signal was determined by the products of oxygen interaction with fullerene rather than the concentration of oxygen in the sample.

Fullerite C60 with intercalated CH2F2 (Freon-32) was prepared for the first time. The sample was studied by elemental analysis, X-ray powder diffraction, mass spectrometry, and IR spectroscopy. The composition of the sample was found to be (CH2F2)C60. The sample had a face-centered cubic lattice with the lattice parameter (1.4284 nm) much larger than that of pure fullerite (1.416 nm). The gas released from the sample during heating in a vacuum to 450°C largely consisted of initial Freon (mass spectrometry data); no Freon destruction products were observed at this temperature. The C-F stretching vibration frequency (1058 cm−1) was shifted in (CH2F2)C60 by 30 cm−1 toward lower wave numbers compared with the gas phase. The absorption bands at 1182 and 1428 cm−1 (IR active modes (F1u) of high-symmetry (Ih) C60 molecules) did not change their positions in the intercalate.

We have prepared ferromagnetic barium hexaferrite powders by self-propagating high-temperature synthesis (SHS) in an electric field applied by a contactless method. Our results indicate that the field strength has a significant effect on the phase composition of the synthesis product. This effect is interpreted in terms of the decomposition kinetics of the solid oxidant and reactant diffusion. Microstructural examination demonstrates that an electric field has a marked effect on the morphology of SHS materials. The magnetic properties of the synthesized powders depend significantly on both the strength and direction of the applied field.

The dependence of the lattice parameters of the chromium oxide Cr2O3 formed in a wave of heterogeneous combustion of chromium (chromium oxide) with sodium and potassium perchlorates on the initial ratio between the fuel and oxidant is established. A new cubic phase of chromium oxide with the lattice parameter close to that of the sodium superperoxide phase is found in the combustion products. The role of the gaseous components in the formation of new phases in the chromium oxide obtained by heterogeneous combustion is determined.

Alkali metal perchlorates are known as oxidizers widely used in propellants, pyrotechnics, catalysts, and other fields [1]. These compounds contain significant proportions of oxygen, so they can also be successfully employed as solid oxidizers in the self-propagating high-temperature synthesis (SHS) of functional oxide materials (ferrites, ferroelectrics, high- T c superconductors, and others) [2]. In the combustion synthesis of complex oxides, the quality of the ultimate product is significantly affected by the degree of coincidence of the peak of perchlorate decomposition with oxygen gas evolution and the peak of metal fuel oxidation [3]. Usually, numerous test-and-trial experiments are needed to solve this problem and to find an optimal batch composition. In this context, it is pertinent to search for means of controlling such processes, especially for distant control means. It was discovered that, for example, strong electric fields generated by a condenser under SHS conditions substantially change the combustion process parameters [4]. The magnetic parameters of some ferrites are substantially modified during SHS in electric fields. To explain the effect of external physical actions on combustion and phase formation during the synthesis of complex oxide materials, it was hypothesized that electromagnetic fields applied to the zone of intense chemical reactions affect the kinetics of the decomposition of solid intrareaction oxidizers [5]. In addition, it cannot be ruled out that such actions affect oxygen exchange during the formation of complex oxides. In order to elucidate possible effects of electric fields, we believed it important to recognize the major SHS stages and to analyze the field effects on each stage. In this context, by way of example we studied the decomposition kinetics in electric fields for pure sodium perchlorate. The experimental setup used to study sodium perchlorate thermolysis (Fig. 1) was a vertical furnace equipped with a kanthal wire heater, with two tubular chambers 20 mm in inner diameter. The furnace was mounted between two copper plates, which were isolated with Teflon liners 1 mm thick and to which voltage up to 25 kV could be applied. Crucibles 18 × 24 mm in size, one containing powdered sodium perchlorate and the other containing a reference (NaCl), were simultaneously inserted into the chambers preheated to the required temperature ( 750°C ). Chromel‐ Alumel thermocouples were embedded beforehand into the powder to a depth of about 3 mm. Thermocouple signals were recorded with a potentiometer equipped with an xy plotter. Sodium perchlorate (99+%) from Acros Organics pounded in an agate mortar with a pestle was used in the experiments.