Coherent-scattering Regions Research Articles

Tribological Properties of Nitrate Graphite Foils.

This study investigates the tribological properties of graphite foils (GF) with densities of 1.0, 1.3, and 1.6 g/cm3, produced from purified natural graphite of different particle sizes (40-80 μm, 160-200 μm, >500 μm). Surface roughness was measured after cold rolling and friction testing at static (0.001 mm/s) and dynamic conditions (0.1 Hz and 1 Hz). Results showed that static friction tests yielded similar roughness values (Sa ≈ 0.5-0.7 μm, Sq ≈ 0.5-1.0 μm) across all densities and particle sizes. Dynamic friction tests revealed increased roughness (Sa from 0.7 to 3.5 μm, Sq from 1.0 to 6.0-7.0 μm). Friction coefficients (µ) decreased with higher sliding speeds, ranging from 0.22 to 0.13. GF with 40-80 μm particles had the lowest friction coefficient (µ = 0.13-0.15), while 160-200 μm particles had the highest (µ = 0.15-0.22). Density changes had minimal impact on friction for the 40-80 μm fraction but reduced friction for the 160-200 μm fraction. Young's modulus increased with density and decreased with particle size, showing values from 127-274 MPa for 40-80 μm, 104-212 MPa for 160-200 μm, and 82-184 MPa for >500 μm. The stress-strain state in the graphite foil samples was simulated under normal and tangential loads. This makes it possible to investigate the effect of the anisotropy of the material on the stress concentration inside the sample, as well as to estimate the elasticity modulus under normal compression. Structural analyses indicated greater plastic deformation in GF with 40-80 μm particles, reducing coherent-scattering region size from 28 nm to 24 nm. GF samples from 160-200 μm and >500 μm fractions showed similar changes, expanding with density increase from 18 nm to 22 nm. Misorientation angles of GF nanocrystallites decreased from 30° to 27° along the rolling direction (RD). The coherent scattering regions of GF with 40-80 μm particles increased, but no significant changes in the coherent scattering regions were observed for the 160-200 μm and >500 μm fractions during dynamic friction tests. Microstrains and residual macrostresses in GF increased with density for all fractions, expanding under higher friction-induced loads. Higher values of both stresses indicate a higher level of accumulated deformation, which appears to be an additional factor affecting the samples during friction testing. This is reflected in the correlation of the results with the roughness and friction coefficient data of the tested samples.

The Influence of Machining Conditions on the Orientation of Nanocrystallites and Anisotropy of Physical and Mechanical Properties of Flexible Graphite Foils.

The physical and mechanical properties and structural condition of flexible graphite foils produced by processing natural graphite with nitric acid, hydrolysis, thermal expansion of graphite and subsequent rolling were studied. The processes of obtaining materials and changing their characteristics has been thoroughly described and demonstrated. The structural transformations of graphite in the manufacture of foils were studied by X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM). A decrease in the average size of the coherent scattering regions (CSR) of nanocrystallites was revealed during the transition from natural graphite to thermally expanded graphite from 57.3 nm to 20.5 nm at a temperature of 900 °C. The rolling pressure ranged from 0.05 MPa to 72.5 MPa. The thickness of the flexible graphite foils varied from 0.11 mm to 0.75 mm, the density-from 0.70 to 1.75 g/cm3. It was shown that with an increase in density within these limits, the compressibility of the graphite foil decreased from 65% to 9%, the recoverability increased from 5% to 60%, and the resiliency decreased from 10% to 6%, which is explained by the structural features of nanocrystallites. The properties' anisotropy of graphite foils was studied. The tensile strength increased with increasing density from 3.0 MPa (ρ = 0.7 g/cm3) to 14.0 MPa (ρ = 1.75 g/cm3) both in the rolling direction L and across T. At the same time, the anisotropy of physical and mechanical properties increased with an increase in density along L and T to 12% with absolute values of 14.0 MPa against 12.5 MPa at a thickness of 200 μm. Expressed anisotropy was observed along L and T when studying the misorientation angles of nanocrystallites: at ρ = 0.7 g/cm3, it was from 13.4° to 14.4° (up to 5% at the same thickness); at ρ = 1.3 g/cm3-from 11.0° to 12.8° (up to 7%); at ρ = 1.75 g/cm3-from 10.9° to 12.4° (up to 11%). It was found that in graphite foils, there was an increase in the coherent scattering regions in nanocrystallites with an increase in density from 24.8 nm to 49.6 nm. The observed effect can be explained by the coagulation of nanocrystallites by enhancing the Van der Waals interaction between the surface planes of coaxial nanocrystallites, which is accompanied by an increase in microstrains. The results obtained can help discover the mechanism of deformation of porous graphite foils. The obtained results can help discover the deformation mechanism of porous graphite foils. We assume that this will help predict the material behavior under industrial operating conditions of products based flexible graphite foils.

Investigating aging processes and characterization of nanodispersed Cu-Al layered double hydroxides produced by non-equilibrium electrochemical oxidation

The present paper describes an investigation of aging processes and the characterization of nanodispersed materials prepared by non-equilibrium electrochemical oxidation of metals. X-ray diffraction (XRD), differential scanning calorimetry (DSC), transmission electron microscopy (TEM) analyses, and the reflectance spectra investigation were used to characterize the electrolysis products aged naturally over time. The ageing of electrolysis products in the solution leads to the conversion of Cu2O-AlOOH into Cu-Al layered double hydroxides (Cu-Al-CO3-LDH) and Cu2(OH)2CO3 due to the Jahn-Teller effect. Long-term aging results in: (i)stability of phase composition but a slight increase of the interplanar spacing due to the sorption ability of the nanostructures in air; (ii) temperature decrease of Cu-Al-CO3-LDH decomposition from 135 to 121 °C due to the stability deterioration with further content increase of carbonate ions (DSC analysis) and decrease of hydroxide ions (FT-IR analysis); (iii) 2.5times increase of the coherent scattering region (CSR) of all copper-containing compounds compared with short-term aging (40–50 nm vs. 15–20 nm); and (iv) no size change of the flower-like Cu-Al-CO3-LDH and dramatical size decrease of nanodispersed particles of CuO and Cu2(OH)2CO3 because of deagglomeration. Conversion CuO/Al2O3 to Cu-Al-CO3-LDH makes a positive impact on photocatalytic activity of nanodispersed materials while it results in the increase the reflection coefficient.

Preparation of Fe-Si-B-(Cu,Nb,Ni,Mo) films by quenching from a vapor state

Using modernized three-electrode ion-plasma sputtering, homogeneous thin films of Fe-Si-B-(Cu, Nb), and Fe-Si-B-(Ni, Mo) were obtained. The structure of the films was investigated by X-ray diffraction and electron microscopy. It was established that as a result of sputtering, amorphous and nanocrystalline phases with a coherent scattering region (CSR) size of 1.6 nm and 12 nm were formed in the Fe73Si16B7-(Cu, Nb)4 and Fe78.5Si6B14-(Ni, Mo)1.5 films. The thermal stability of metastable states of the films, as well as theelectrical and magnetic properties of freshly prepared and heat-treated films were studied. The conditions for obtaining films with small (modulo) values of the temperature coefficient of electrical resistance ( - 0.9∙10-5 K-1) and coercive force (HC ~ 11 A/m) were determined.

Synthesis of Two-Dimensional NiO Nanostructures by a Combination of Programmable Chemical Deposition and Hydrothermal Treatment

The synthesis of two-dimensional NiO nanostructures by programmable chemical deposition in combination with the hydrothermal treatment of intermediates in distilled water and in aqueous ammonia solution was studied. Simultaneous thermal analysis was used to determine the dependence of thermal stability and sorption capacity of particles of the intermediates on the parameters of their hydrothermal treatment and on the composition of the dispersion medium. The results of IR spectroscopy and X-ray diffraction analysis helped us to recognize the crystal structure specifics and the set of functional groups for intermediates and for NiO nanopowders formed on their basis. The average size of the coherent scattering regions (CSRs) of the manufactured nickel oxide powders varied from 4.0 ± 0.5 to 8.6 ± 0.8 nm depending on the hydrothermal treatment parameters. Scanning (SEM) and transmission (TEM) electron microscopy showed that the recrystallization of NiO nanoparticles can be tuned depending on the synthesis parameters to yield two-dimensional nanostructures of various shapes and required sizes, ranging from nanosheets of chaotic geometry to flat hexagons with a variable diameter. Due to their anisotropic microstructure, the manufactured nanomaterials can be effectively used in the fabrication of functional components for advanced alternative energy devices (supercapacitor electrodes, solid oxide fuel cells, etc.), including the use of printing technologies.

Surface nano-crystallisation and mechanical properties of Ti[sbnd]Ta composite materials after surface mechanical grinding treatment

Surface mechanical milling generates gradient nano-structure surfacial layers that enhance the mechanical properties of titanium (Ti)–tantalum(Ta) composites for medical implants. Herein, the effect of surface mechanical grinding treatment (SMGT) on the surface nano-crystallisation of TiTa laminated composites was investigated in terms of micro-structure and Coherent Scattering Regions (CSRs) size using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. A strengthening effect was verified using a micro-hardness tester and tensile testing machine, and the fracture mechanism was analysed through fracture observation. The experimental results showed that gradient nano-structures were formed on the surface of the TiTa laminated composites after SMGT, with the smallest CSRs size of the outer surface layer of approximately 13.3 ± 0.4 nm. The plastic deformation mechanism of the TiTa laminated composites during SMGT was a dislocation cutting mechanism. The micro-hardness and tensile strength of the TiTa laminated composites increased after SMGT up to 440 HV and 1097.528 MPa, respectively. The fracture mechanism of the TiTa laminated composites after SMGT was a combination of ductile fracture and quasi-cleavage fracture mechanisms. After SMGT, the TiTa laminated composite performed well and exhibited excellent potential for use in biomaterials.

Investigating Spatial and Temporal Structuring of E‐Region Coherent Scattering Regions Over Northern Norway

AbstractRecently, it has been shown that the Spread Spectrum Interferometric Multistatic meteor radar Observing Network radar system located in northern Norway is capable of measuring ionospheric E‐region coherent scatter with spatial and temporal resolutions on the order of 1.5 km and 2 s, respectively. Four different events from June and July of 2022 are examined in the present study, where the coherent scatter measurements are used as a tracer for large‐scale ionospheric phenomena such as plasma density enhancements and ionospheric electric fields. By applying a two‐dimensional Fourier analysis to range‐time‐intensity data, we perform a multi‐scale spatial and temporal investigation to determine the change in range over time of large‐scale ionospheric structures (>3 km) which are compared with line‐of‐sight velocities of the small scale structures (∼5 m) determined from the Doppler shift of the coherent scatter. The spectral characteristics of the large‐scale structures are also investigated and logarithmic spectral slopes for scale sizes of 100–10 km were found to be between −3.0 and −1.5. This agrees with much of the previous work on the spatial spectra scaling for ionospheric electric fields. This analysis aids in characterizing the source of the plasma turbulence and provides crucial information about how energy is redistributed from large to small scales in the E‐region ionosphere.

Photoadsorption of Cr(VI) on titanium dioxide modified by high-energy milling

Microcrystalline powders of rutile and anatase were milled in a high-energy planetary mill down to obtain nanosized TiO2 powders (the size of coherent scattering region (CSR) about 30 nm and 60 nm, respectively). The resulting powders were characterized by HRTEM, Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and the ξ-potential of the aqueous suspensions was determined. High-energy milling made it possible to significantly increase the ability of TiO2 to remove chromium from aqueous solutions. The effectiveness of the powders for not only Cr(VI) removing but also total chromium adsorption under UV-irradiation and short wavelength visible light has been shown. This is important, since Cr(III) does not remain in the aqueous medium and cannot be oxidized back to Cr(VI) under the influence of some environmental factors. It is possible to remove more than 99.9% of total chromium and 100 % of chromium hexavalent from a 50 mg·L-1 solution of Cr(VI) using milled anatase. XPS showed that, upon the photoadsorption, Cr(VI) is reduced to Cr(III). The presence of an acetate buffer in the solution promotes the most efficient removal of chromium. This work shows a simple way to obtain a highly effective material with potential applications for the removal of high toxic hexavalent chromium from industrial wastewater. The milled anatase sample was successfully tested to remove Cr (VI) from a real wastewater sample.

Effect of Synthetic Approaches and Sintering Additives upon Physicochemical and Electrophysical Properties of Solid Solutions in the System (CeO2)1−x(Nd2O3)x for Fuel Cell Electrolytes

Finely dispersed (CeO2)1−x(Nd2O3)x (x = 0.05, 0.10, 0.15, 0.20, 0.25) powders are synthesized via liquid-phase techniques based on the co-precipitation of hydroxides and co-crystallization of nitrates. The prepared powders are used to obtain ceramic materials comprising fluorite-like solid solutions with the coherent scattering region (CSR) of about 88 nm (upon annealing at 1300 °C) and open porosity in the range of 1–15%. The effect of the synthesis procedure and sintering additives (SiO2, ZnO) on physicochemical and electrophysical properties of the resulting ceramics is studied. The prepared materials are found to possess a predominantly ionic type of electric conductivity with ion transfer numbers ti = 0.96–0.71 in the temperature range of 300–700 °C. The conductivity in solid solutions follows a vacancy mechanism with σ700 °C = 0.48 × 10−2 S/cm. Physicochemical properties (density, open porosity, type and mechanism of electrical conductivity) of the obtained ceramic materials make them promising as solid oxide electrolytes for medium temperature fuel cells.

EVOLUTION OF THE DEFECT STRUCTURE OF Pd–11.3 at. % W ALLOY DURING RELAXATION AT MULTIPLE HYDROGENATION

The influence of the hydrogen and vacancies introduced into an alloy matrix as a result of electrolytic hydrogenation on the structural state of Pd–11.3 at % W alloy after fourfold hydrogenation has been studied. It is established that nonmonotonic changes in the sample defect structure are determined by the transformation of single vacancies into vacancy complexes (micropores and small dislocation loops), their decay during relaxation, and migration of vacancies from the matrix to the boundaries of coherent-scattering regions (CSRs) and backwards. The vacancy transformation rate into defect complexes depends on their concentration. Long-term relaxation of the alloy leads to almost complete transfer of vacancies from the matrix to the CSR boundaries. An interpretation of the obtained experimental data within the theory of development of hierarchical defect structures is proposed.

Atmospheric Pressure Solvothermal Synthesis of Nanoscale SnO2 and Its Application in Microextrusion Printing of a Thick-Film Chemosensor Material for Effective Ethanol Detection.

The atmospheric pressure solvothermal (APS) synthesis of nanocrystalline SnO2 (average size of coherent scattering regions (CSR)-7.5 ± 0.6 nm) using tin acetylacetonate as a precursor was studied. The resulting nanopowder was used as a functional ink component in microextrusion printing of a tin dioxide thick film on the surface of a Pt/Al2O3/Pt chip. Synchronous thermal analysis shows that the resulting semiproduct is transformed completely into tin dioxide nanopowder at 400 °C within 1 h. The SnO2 powder and the resulting film were shown to have a cassiterite-type structure according to X-ray diffraction analysis, and IR spectroscopy was used to establish the set of functional groups in the material composition. The microstructural features of the tin dioxide powder were analyzed using scanning (SEM) and transmission (TEM) electron microscopy: the average size of the oxide powder particles was 8.2 ± 0.7 nm. Various atomic force microscopy (AFM) techniques were employed to investigate the topography of the oxide film and to build maps of surface capacitance and potential distribution. The temperature dependence of the electrical conductivity of the printed SnO2 film was studied using impedance spectroscopy. The chemosensory properties of the formed material when detecting H2, CO, NH3, C6H6, C3H6O and C2H5OH, including at varying humidity, were also examined. It was demonstrated that the obtained SnO2 film has an increased sensitivity (the sensory response value was 1.4-63.5) and selectivity for detection of 4-100 ppm C2H5OH at an operating temperature of 200 °C.

Synthesis and Characterization of Ceria- and Samaria-Based Powders and Solid Electrolytes as Promising Components of Solid Oxide Fuel Cells

Finely dispersed (CeO2)0.95(Sm2O3)0.05, (CeO2)0.90(Sm2O3)0.10 and (CeO2)0.80(Sm2O3)0.20 mesoporous powders with a specific pore volume of 0.080–0.092 cm3/g and a specific surface of 50–83 m2/g are synthesized by the co-precipitation of cerium and samarium hydroxides from the corresponding nitrate solutions. The prepared powders are used to obtain ceramic nanomaterials with a fluorite-like cubic crystal lattice with a coherent scattering region (CSR) of about 65–69 nm (1300 °C). The study of physicochemical and electrophysical properties of the prepared ceramics revealed the obtained materials featuring an open porosity of 2–6% and a predominantly ionic type of electric conductivity (ion transport numbers ti = 0.85–0.73 in the temperature range 300–700 °C). The conductivity in solid solutions proceeds via a vacancy mechanism with σ700 °C= 3.3·10−2 S/cm. The synthesized ceramic materials are shown to be promising as solid oxide electrolytes in medium temperature fuel cells.

Potential impact of dispersion products of magnetite quartzites on the environment

Using XRF, TG-DTA, chemical and sedimentation analysis of the products of processing of magnetite quartzites from the N Ore Processing Plant of Krivorozhye, changes in the phase and chemical composition of samples of four stages of magnetic separation and tailings were traced compared to a sample of the raw ore, and the potential impact of the dispersion process on the environment was revealed. Thermogravimetric studies indicate phase transformations of magnetite to maghemite (250-340 ° C), polymorphic transformations of iron oxides and destruction of rock-forming minerals (430-480 ° C), conversion of alpha quartz to beta-form (564-568 ° C), dehydroxylation of iron and magnesium oxyhydroxides (385 ° C), conversion of beta-quartz to beta-cristobalite (970 ° C). In the process of enrichment, there is an increase in the loss of mass of the samples, which is %: 0.06 (I); 1.46 (II); 1.9 (III), and 2.6 (IV). According to X-ray diffraction, the main ore mineral is magnetite, the rock-forming mineral is quartz. Among the secondary minerals are sulfides, cummingtonite, actinolite, and others. It is shown that at the first stage of enrichment all primary and secondary minerals are present in the samples, at the 2nd stage sulfides disappear from the sample, at the 3rd stage secondary minerals disappear, and at the 4th stage quartz remains in the sample and it forms aggregates with magnetite. The parameter of the crystal lattice of magnetite varies between 8.397-8.403 nm, its coherent scattering region (CSR) is 31.4-35.6 nm. It is found that in the course of ore grinding the destruction of secondary minerals takes place with the removal of destruction products, as evidenced by the occurrence of disperse quartz in the tailings. According to sedimentation analysis data, in the first 20 seconds, more than half of the particles with a size of 24-28 μm were deposited from the pulp, after 3 minutes, particles with a size of 8-9 μm settled, after 6 minutes - particles with a size of 6-7 μm. Within 30 minutes, almost complete precipitation of particles with sizes of 4.5-2.7 μm was observed. Hydraulic classification of the tailings showed the deposition of mainly quartz particles in the first and second chambers of the separator, actinolite and muscovite particles were separated in the third chamber, and cummingtonite, biotite and chlorite in the fourth chamber. Analysis of the chemical composition of the dispersion products indicates that Si, Ca, and Na accumulate in the tailings, whereas Ti is removed, and could potentially enter the environment. It is shown that the tailings and separation products increase the content of Zn, and the tailings accumulate environmentally hazardous As, and Nb. At the same time, the concentrations of other elements remain stable at all stages of processing.

Friction-induced phase transformations and evolution of microstructure of austenitic stainless steel observed by operando synchrotron X-ray diffraction

A materials’ structure and its evolution due to friction play a crucial role in understanding wear and related processes. So far, structural changes caused by friction are mostly studied using ex situ destructive characterization techniques, such as microscopy of post-mortem the prepared specimen by polishing and etching techniques. In this paper, the structural changes of AISI 321 austenitic stainless steel (ASS) during frictional loading were observed by the nondestructive operando method based on synchrotron X-ray diffraction (XRD). Although the martensitic transformation in AISI 321 steel starts at ca. -187 °C, frictional loading induces γ-(ε, α′) transformation in this alloy at room or even higher temperatures. The ε-martensite formation is observed only for a relatively short time. Subsequently, a mechanically-mixed layer (MML), composed mainly of the α′ phase, forms at the sample’s surface. Using XRD peak profile analysis, we observed the accumulation of dislocations, their ordering, and/or stress field shielding before and after phase transformations. The steady-state conditions are reached after ca. 69 friction cycles manifested in reaching the threshold values of the size of the coherent scattering regions (CSRs) and dislocation density in γ and α′ phases. For a better understanding of structural evolution, the microstructure of the sample was studied by scanning electron microscopy (SEM) after the experiment. The structure of the MML, its delamination, the formation of vortices, and carbide crushing are discussed.

Changes in the physicochemical and catalytic properties of iron-potassium catalysts during their operation in a reactor for ethylbenzene to styrene dehydrogenation at PJSC «Nizhnekamskneftekhim»

The paper presents the results of studying the iron-potassium catalysts for dehydrogenation of ethylbenzene (EB) to styrene, both fresh and spent, under industrial conditions: Cat-1 (imported), Cat-2 and Cat-3 (domestic). The initial samples are the multiphase systems consisting of potassium ferrites, hematite and cerianite (CeO2). After two years of operation, the phase composition of the catalysts was represented mostly by magnetite and cerianite, and potassium (K+) content in Cat-1, Cat-2 and Cat-3 samples decreased by 40, 20 and 26 %, respectively. Therewith, the Cat-2 sample retained a uniform K+ distribution in the spent catalyst grain. According to XRD data, the coherent scattering region (CSR) of CeO2 crystals in this sample did not change significantly. In the Cat-3 sample, the CSR size of CeO2 crystals decreased from 302 to 110 Å, while in Cat-1 it increased from 284 to 419 Å. After a two-year operation, the highest EB conversion equal to 72.1 % was observed on the Cat-2 sample, whereas on Cat-3 it decreased from 72.3 to 57.4 %. A 6÷11-fold decrease in the crushing strength was found for the spent samples, which made them unsuitable for further application.

Properties of cerium (III) fluoride nanopowder obtained by pulsed electron beam evaporation

The method of pulsed electron beam evaporation (PEBE) 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. The main physicochemical characteristics of NP were studied: structure, porosity, thermal stability and magnetic properties. It was found that the produced NP contains two crystalline phases: hexagonal CeF3 (95 wt%, coherent scattering regions (CSR) ≈ 8 nm) and [Ce-O-F] or [Ce-F]. The last phase is obtained only at a high temperature, which is characteristic for the used NP synthesis method. 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 (SSA) (CeO2–270 m2/g, CeF3 - 62 m2/g) and large pore volume (0.35–0.11 cm3/g) allow the use of NP as nanocontainers for drug delivery.

Morphological and magnetic features of columnar nanostructures CuO

Columnar nanostructures (CNS) were grown by plasma chemical synthesis at a gas mixture pressure of 90% He + 10% O2 200 Pa and substrate temperatures of 340K (sample 1) and 370K (sample 2). The effect of substrate temperature on the morphological, crystalline, magnetic, and impedance properties of CNS was studied. Scanning microscopy (SEM) showed that the morphology of CNS varies significantly from dendritic to wire structure. Energy dispersive X-ray spectroscopy (EDS) showed a change in the stoichiometry of the deficiency samples (Cu52O48) to an excess of oxygen (Cu42O58). X-ray diffraction analysis (XRD) and Rietveld fitting showed that samples 1 and 2 have a monoclinic crystal structure with a large proportion of the amorphous phase, the size of coherent scattering regions (CSR) was 26 nm (sample 1). Magnetic measurements showed that sample 1 exhibits ferromagnetic behavior, and at 6 K a magnetic hysteresis loop appears. Sample 2 from 250 K to room temperature exhibits diamagnetic behavior. A connection was found between the appearance of diamagnetism and a jump in the dielectric constant of sample 2. An assumption was made about the electron-ionic nature of the diamagnetism of sample 2.

Microstructure and local electrophysical properties of sol-gel derived (In2O3-10%SnO2)/V2O5 films

Sol-gel synthesis of thin In2O3-xSnO2 (x = 5–15 mol% SnO2) films and double-layer (In2O3-10%SnO2)/V2O5 nanostructures utilizing hydrolytically active metal alkoxoacetylacetonate complexes [M(C5H7O2)x(C4H9O)y] (M = In3+, Sn4+) and [VO(C5H7O2)2-z(C4H9O)z] as precursors was studied. Dependencies of mean coherent scattering regions (CSR) and particle size, specific resistance, work function, band gap and transmittance in visible region on tin dioxide contents in obtained In2O3-xSnO2 films were determined and attributed to changes in crystal lattice parameter and oxygen vacancies amount. For (In2O3-10%SnO2)/V2O5 bilayer thin film nanostructures, microstructural and local electrophysical properties were studied. It was shown that vanadium (V) oxide deposited on the surface of In2O3-10%SnO2 film constitutes a coating made of hemispherical clusters of about 180 nm diameter and mean height of 80 nm, with distance between clusters being roughly 100–500 nm and clusters themselves showing good conductivity.

The spinodal decomposition in the BST system

A study of Ba1-xSrxTiO3 solid solutions (0.00 ≤ x ≤ 1.00) prepared by conventional ceramic technology have been performed. By the X-ray diffraction method, a discrepancy between the phase diagram (room temperature) of the quasi-binary system BaTiO3-SrTiO3 and the well-known phase diagram is established. According to the latter, at x ≈ 0.3, there is a transition from the tetragonal phase to the cubic phase. Our study revealed a splitting of diffraction peaks in the cubic phase (0.3< x <0.7), a bimodal distribution of particles in solid solutions, and sinusoidal modulation of the structure. The concentration dependences of the coherent-scattering region and the microstrains do not correspond to the phase transition by the of nucleation and growth mechanism. The ferroelectric → paraelectric phase transition in the solid solutions with x = 0.1, 0.2 is a first-order transition, and with x = 0.3, it is the second-order transition or close to it. The dielectric spectra of solid solutions with x = 0.1 and x = 0.2 are characterized by strong dispersion, an increase in the dielectric constant at low frequencies and a giant increase dielectric constant in the solid solution with x = 0.2. The conclusion about spinodal decomposition of Ba1-xSrxTiO3 solid solutions in the range of 0.275 ≤ x <0.800 at room temperature was made.

Studies of water treatment influence on the structure of vein quartz from shungite rocks

The article presents the results of the research of the structure and composition of one of the morphological varieties of quartz – vein quartz of shungite rocks from Zazhogino deposit of Karelia and a reference quartz sample. The values of the crystal lattice parameters were determined by full-profile analysis (Rietveld method). Coherent scattering region (CSR) for vein quartz samples are determined using the Debye-Scherrer formula after applying the background subtraction function. The influence of water treatment on the content of impurity elements in samples of vein quartz was also studied. The most common impurity elements in natural vein quartz samples, such as Al, Na, Li and Ge, are identified. It is shown that water treatment is effective for reducing the content of impurity elements and obtaining the minimum size of vein quartz crystallites.