Production of nanopowder of cerium (III) fluoride obtained by pulsed electron beam evaporation in vacuum

The method of pulsed electron beam evaporation in vacuum was first used to obtain CeF3 nanopowder (NP). During NP production, a high evaporation rate of the target (~ 7 g/h) and a higher percentage of NP collection (> 72%) were observed, both for fluoride and the previously obtained CeO2 oxide. It was found that the produced NP contains two crystalline phases: hexagonal CeF3 (95 wt.%, coherent scattering region ≈ 8 nm and [Ce-O-F] or [Ce-F]. The magnetic susceptibility of CeF3 nanoparticles (NPles) coincides with the susceptibility of micron particles, indicating the potential for using such NPles as a contrast agent for tomography. High specific surface area (CeO2-270 m2/g, CeF3 – 62 m2/g), large pore volume (0.35-0.11 cm3/g) allow the use of NPles as nanocontainers for drug delivery.

Characterization of size and morphological composition of ablated nanoparticles of cerium dioxide after ultrasonic dispersion and centrifugation in aqueous solution

The paper investigates the size and morphological composition of ablated cerium dioxide nanoparticles after ultrasonic dispersion at centrifugation speeds from 800 to 13400 rpm. A nanodispersed solution of cerium dioxide was deposited onto silicon substrates by the drop method. To characterize the size and morphological composition of cerium dioxide nanoparticles, methods of scanning electron and atomic microscopy were used, and X-ray phase analysis was performed. It was found that ablated cerium dioxide particles in an aqueous solution agglomerated and without centrifugation their average size was 162 nm, after centrifugation their average size varied from 86 nm to 142.5 nm. X-ray phase analysis showed that with an increase in the centrifuge speed, the size of the coherent scattering region decreases, which affects the effectiveness of antioxidant properties, for example, in the Fenton reaction.

Water vapor adsorption/desorption on granulated binder-free low-module zeolites

A characteristic of granulated LTA and SOD zeolites is given. It was determined that LTA zeolite particles have a cube shape with a size of ~2 μm; SOD particles have an irregular shape with a size of 0.5–1 μm. The dimension of the coherent scattering region was calculated to be 760 nm for LTA and 453 nm for SOD. The specific surface area of LTA is 115 m2·g–1 and SOD is 141 m2·g–1. Static tests of granulated zeolite showed that the maximum quantity of absorbed water vapor for LTA was ~30 wt.%, and for SOD ~20 wt.%. It was found LTA zeolite to provide adsorption of water from the gas to a dew point of –50 °C, and SOD zeolite of –9 °C. The apparent activation energies for the desorption of water on zeolites were calculated using isoconversional analysis of Friedman, Ozawa–Flynn–Wall, and Kissinger–Akahira–Sunose.

Synthesis and electrochemical properties of LaMnO3 orthosized nanomaterial for supercapacitor applications

In this work, the perovskite LaMnO3 material has been prepared based on the sol-gel process of synthesis with the participation of combustion. According to the X-ray phase analysis, it was determined that the obtained material consists of LaMnO3 one phase (space group Pm-3m). Nevertheless, it has been determined that the average size of the coherent scattering region of the obtained material is about 24 nm. Moreover, the average particle size is 40-60 nm in case the approximation that the particles are spherical shape. Thus, it has been determined that the specific surface area of the material is 42.1 m2/g. The electrochemical investigations have been performed using nanosized LaMnO3 powder as a cathode material for electrochemical capacitors. The LaMnO3 material under research showed a specific capacity of 40 F/g at a discharge of up to 1V.

GRANULATED LOW-MODULUS ZEOLITES FOR EXTRACTION OF CO CATIONS

The paper gives a characteristic of LTA and SOD zeolite pellets, which were synthesized using preliminary ultrasonic processing. By X-ray diffraction and IR spectroscopy methods, it was established that the investigated samples contained about 100% of the LTA or SOD phase. It was shown that zeolite LTA particles have a dimension of coherent scattering region of 780 nm and root mean square microdeformations of 0.05%, while SOD zeolite particles have this parameter about 460 nm and the defectiveness of crystal lattice is 0.15%. The values of the specific surface area of zeolite pellets were determined, the values of which are 148.8 and 115.6 m2/g for LTA and SOD, respectively. It was noted that the SOD zeolite pellets have virtually no micropores. Equilibrium curves were obtained for the saturation of zeolite pellets with cobalt cations depending on the concentration of Co2+ in an aqueous solution of cobalt chloride. It was shown that in the entire investigated range of Co2+ concentrations, the LTA zeolite capacity is 30% higher than that of the SOD zeolite which can be explained by two main reasons. Firstly, this is a higher specific surface area of the LTA zeolite. Secondly, these are structural features of the zeolite frameworks, namely, LTA zeolite has α-cavities which are more accessible for Co2+. It is also shown that with increasing temperature, the zeolites capacity on cobalt cations grows. It was discovered that a new absorption band with a wave number at 1390 cm–1 appears on the IR spectra of both zeolites after saturation. In addition, an increase in the size of the unit cell and a growth in the defectiveness of particles were noted in cobalt-saturated zeolites. Taken together, these facts point to the cation exchange. It was shown that 1 g of LTA zeolite provides almost complete purification of 50 ml of the solution from 57Co cations in a dynamic mode.

Deposition of superhard Ti-C-N plasma coatings in nitrogen atmosphere

The possibility of obtaining a superhard plasma coating based on titanium, nitrogen and carbon on a metal substrate in a nitrogen atmosphere is shown. The coatings were deposited in one short-term accelerator operation cycle under the action of a hyperspeed jet of electroerosive Ti-containing plasma on the substrate surface. It has been shown by SEM and XRD that nanostructured layers of titanium nitride and titanium carbonitride are formed, providing a high hardness of the coating. Plasma coatings deposited in a nitrogen atmosphere have a higher hardness (19.6 GPa) than coatings deposited in air (16.2 GPa), which is due to a higher content of nitride crystalline phases in the coating material. XRD data showed that the coherent-scattering region of crystalline phases in coatings deposited in an atmosphere of air and in a nitrogen atmosphere is ~10-40 nm, which confirms the nanostructuring of all crystalline phases presented in the coating.

Changes in the Structural and Morphological Parameters of Fe2O3/SiO2, as a Basis for the Electrode Material of Lithium Power Sources, Due to Shock-Vibrating Treatment

Using the method of X-ray diffraction, the effect of shock-vibration treatment on the structural parameters and phase composition of mixtures of silicon dioxide and alpha iron oxide was studied. From these results, has been found that the shock-vibration treatment of oxides mixture leads to an increase in the coherent scattering region of crystalline α-Fe2O3. We obtained SEM images of composites before and after treatment. From the SEM images it is seen that the processing is accompanied by fragmentation of the aggregates, uniform placement of the nanoparticles between each other and the formation of new denser agglomerates. Electron-microscopic study of mixtures using TEM was performed, which showed that the treatment leads to a lay-up of particles each other with the formation of interatomic interaction between them, which is consistent with the results of ultra-soft X-ray emission spectroscopy. The electrochemical properties of LPS, with electrodes based on mixtures before and after treatment, in galvanostatic mode were investigated. It is found that the charge capacity of the LPS with the electrode based on the mixture with the maximum concentration of α-Fe2O3 after treatment is reduced by half.

Mineral-polymer composites based on hydroxyapatite with polyvynylpyrrolidon for medicine

Composites of hydroxyapatite (HA) with polyvinylpyrrolidone (PVP) were synthesized by precipitation in water solutions, mass relations of HA/PVP varied in region 3,6-14,5. The composite materials were investigated using XRD, IR, electron paramagnetic resonance (EPR) spectroscopy and transmission electron microscopy (TEM). Based on the TEM results it was found that during calcination of composites at 400 °C small agglomerates consisting of individual crystalline HA particles were formed, resulting in a particle size (according to TEM) slightly larger than coherent scattering region. Using the method of photoinduced EPR spectroscopy confirmed the presence of interaction between HA and PVP. The resulting composites can be used as materials for reconstructive surgery.

Исследование длинноволновых инфракрасных спектров отражения моно- и поликристаллов SmS в области гомогенности

The far- and mid-IR reflection spectra of Sm_1 + x S ( x = 0–0.17) samples are recorded and analyzed, as well as their electrical and structural parameters at a temperature of T = 300 K. The bond ionicity in SmS is shown to fall with a decrease in the area of the X-ray coherent scattering region and an increase in the concentration of donor impurities and, consequently, conduction electron concentration. The electrical conductivity of stoichiometric SmS single crystals and polycrystals can be determined with an error of 10% from the IR reflection spectra. Due to the low structural quality of the samples, the electrical conductivity cannot be determined in the case of deviation from stoichiometry.

USE OF MECHANOCHEMICAL ACTIVATION TO CONTROL RHEOLOGICAL PROPERTIES OF MOULDING PASTES FOR CATALYSTS AND SORBENTS EXTRUSION

For citation:Svyatenko N., Prokof’ev V.Yu., Gordina N.E. Use of mechanochemical activation to control rheological properties of moulding pastes for catalysts and sorbents extrusion. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 1. P. 102-107.The influence humidity, grinding and mechanical activation of the solid phase on the rheological properties of the molding paste for extrusion of catalysts and sorbents was studied. The following parameters of the molding pastes were investigated, namely the coagulation structure strength, the flow index, the maximum plastic viscosity, the critical shear stress, plasticity, the r (stuelaxation period), the ratio of deformations. In order to characterize the degree of mechanochemical activation, the dimension of the coherent scattering region and the microdeformations value were used. Increasing the degree of mechanochemical activation of the solid phase was shown to allow controlling the properties of molding pastes in a more wide range. In the technology of extruded catalysts and sorbents, the mills-activators with the impact-shear loading are proposed to use. The mills with an average value of power density (up to 6 kW/kg) were recommended.