Search

The structural and optical properties of lithium–iron oxide and lithium–iron–phosphorus oxide obtained by pyrolytic extraction are compared using X-ray diffraction, vibrational spectroscopy, and Raman spectroscopy. The conditions for the formation of crystalline phases of these disperse materials are established. Using methods of spectroscopy, the material is demonstrated to contain carbon, improving the mobility of electrons. [ABSTRACT FROM AUTHOR]

Iron lithium phosphorus oxide, which is promising for use as a cathode material in lithium-ion batteries, has been synthesized by the extraction-pyrolytic method and further investigated. The possibility of obtaining phosphorus-containing Li–Fe–P–O cathode materials using di-(2-ethylhexyl)phosphoric acid has been shown. Structural and optical studies of Li–Fe–P–O dispersed material have been carried out using X-ray photoelectron spectroscopy and X-ray diffraction. The conditions for the formation of crystalline phases of these dispersed materials have been established. It has been shown using spectroscopic methods that the material contains carbon in its composition, which helps improve electron mobility. [ABSTRACT FROM AUTHOR]

Changes in the mesostructure and hydrothermal stability of the MCM-41 silicate material, depending on the synthesis conditions have been investigated. The mesostructure was characterized by the X-ray structural analysis, adsorption surface measurements, and hydrothermal stability. Changes in the synthesis conditions consisted in changing the reaction solution basicity using ammonia and alkali and replacing the mother liquor used in hydrothermal treatment by water, as well as salt and alcohol-ammonia solutions. The increase of the pore diameter is caused, as a rule, by the water osmotic pressure. Moreover, if the silica polycondensation is slowed or sterically hindered, the pores acquire a hexagonal shape or, under conditions promoting polycondensation, a cylindrical one. Predominance of the hexagonal shape over the cylindrical one points to the reduced hydrothermal stability of the material. Pore wall consists of two-layer silica pack with thickness of 0.08-0.10 nm. Ammonia applying, as reaction medium basicity factor, provides maximal silica polymerisation rate and hight hydrothermal stability of the material. [ABSTRACT FROM AUTHOR]

Known methods for synthesis of a trinuclear molecular form of palladium(II) acetate, [Pd(CHCOO)], are analyzed and a number of new techniques that enable reliable control over the type of the product obtained and provide its high yield are suggested. A molecular transformation scheme is suggested. This scheme takes into account the formation of both forms of palladium acetate and also the formation of the structurally similar [Pd(CHCOO)NO]. [ABSTRACT FROM AUTHOR]

Heterostructures were prepared from MSM molecular sieves and magnetic materials by extraction pyrolysis. The molecular sieves were filled with solutions of extracts and heated to remove the organic phase and form an inorganic material. The annealing and dissolution of the MSM-41 molecular sieve gave nanosized cobalt ferrite powder with particles of 40 nm and a coercive force 5000 Oe. [ABSTRACT FROM AUTHOR]

Crystal structures of [Pd(NH3)2X2] complexes, where X = Br or I, diamminediiodo-I-dibromopalladium(II), have been studied by X-ray powder diffraction. The series consists of five complexes: cis[Pd(NH3)2Br2] (I) [a = 13.3202 (7), b = 12.7223 (6), c = 7.05854 (3) Å, Z = 8, space group Pbca], trans-[Pd(NH3)2Br2] (II) [a = 6.7854 (3), b = 7.1057 (2), c = 6.6241 (2) Å, α = 103.221 (3), β = 102.514 (2), γ = 100.386 (3)°, Z = 2, space group P&1macr;]. β-trans-[Pd(NH3)2Br2] (III) [a = 8.4315 (3), b = 8.4206 (3), c = 8.0916 (2) Å, Z = 4, space group Pbca], cis[Pd(NH3)2I2] (IV) [a = 13.9060 (8), b = 13.5035 (8), c = 7.5050 (4) Å, Z = 8, space group Pbca], and β-trans-[Pd(NH3)2I2] (V) [a = 8.8347 (5), b = 8.8410 (5), c = 8.6081 (2) Å, Z = 4, space group Pbca]. Patterson synthesis and Rietveld refinement have been used for structural determination. Molecular structures with column- or parquet-type packing of flat complexes are characteristics of these substances. Corresponding cis- and β-trans compounds are isostructural. Thet thermal transformations cis→trans→β-trans (cis→β-trans in the case of iodine) are considered. Cl derivatives are also discussed. The transformations proceed irreversibly and are accompanied by decreasing specific volume. Owing to these features, they can be classified as chemical reactions. High-temperature X-ray powder diffraction was used to study the transformations in air. The set of data is consistent with a solid state transformation from cis to trans. According to this model, the columns of molecules remain intact during the process, and the transformation proceeds via the breaking of Pd···X and Pd···N intermolecular bonds. The powder diffraction data have been deposited in ICDD-JCPDS (45-0596, 46-0876, 46-0879, 47-1690, 48-1185). [ABSTRACT FROM AUTHOR]

new method is proposed for the low-temperature production of graphene with high yield. The method is based on the low-temperature synthesis and decomposition of graphite intercalation compounds with sodium ammoniates. The proposed technology retains high efficiency, which is typical of graphene synthesis via graphite oxidation and thermal expansion, and offers new advantages by ensuring high purity and structural perfection of the product. [ABSTRACT FROM AUTHOR]

A photoactive р-Si/p-Cu2O/n-ITO heterostructure synthesized via the pyrolytic-extraction deposition of copper oxide and indium–tin oxide onto a silicon substrate is presented. This method is demonstrated to provide the formation of an electron-hole p-Cu2O/n-ITO junction, thus opening up opportunities for the creation of heterostructural solar cells on large surfaces at decreased expenditures on their production. The presence of transparent conductive oxide ITO creates the conditions for more active photovoltaic conversion. [ABSTRACT FROM AUTHOR]

The use of the 5-phenyl-1H-pyrimidin-6-one scaffold in the search for biologically active compounds with antiviral activity based on the pyrimidin-4-one core present in endogenous substances and drugs was substantiated. The molecular activity and pharmacokinetic descriptors for styryl derivatives of N-substituted 5-phenyl-1H-pyrimidin-6-one were predicted in silico via the SwissADME web service. The lack of crystallographic data and information about the tautomeric form of 2,4-dimethyl-5-phenyl-1H-pyrimidin-6-one necessitated the measurement and analysis of x-ray diffraction patterns of the starting substance to explain the reactivity in the styrylation reaction. New derivatives of 5-phenyl-2-[(E)-styryl]-1H-pyrimidin-6-one were synthesized. Studies of their inhibitory activity toward SARS-CoV-2 major (Mpro) and papain-like proteases (PLpro) revealed their marked antiviral activity. [ABSTRACT FROM AUTHOR]

Results of experimental investigation of thermal properties (thermal conductivity, volumetric heat capacity, coefficient of linear thermal expansion, thermal anisotropy coefficients) of gneisses and dolerites (Krasnoyarsk region, Siberia, Russia) are described in the paper. The work is aimed at the data acquisition for safe deep geological disposal of radioactive waste. About 1500 measurements on more than 50 rock samples were performed totally. The experiments were performed using advanced hardware-methodical base that provided non-contact non-destructive high-precision measurements of thermal conductivity and volumetric heat capacity with continuous high-resolution profiling of these properties on full-size core samples, characterization of rock anisotropy and multi-scale heterogeneity. The numerous thermal profiling resulted in 3D images of thermal conductivity and volumetric heat capacity constructed on cylindrical surfaces of the core samples. Special approaches to experimental data processing were applied to improve representativeness of results. Temperature dependencies of rock thermal conductivity and volumetric heat capacity were characterized within a range of 5–200 °C. Differential and integral coefficients of linear thermal expansion were studied within this temperature range accounting to the rock anisotropy. Essential multi-scale heterogeneity, 2D (textural) anisotropy and microanisotropy of rocks were established and characterized. Significant differences in the thermal properties of gneisses and dolerites were demonstrated. Relationships between thermal conductivity and geomechanical characteristics (Young's modulus, P-wave velocity) of gneisses were specified for a more complete rock characterization. Recommendations for application of the developed advanced hardware-methodical base for experimental investigations of rock massifs for safe disposal of radioactive waste and other goals are given. Highlights: The method of experimental investigations of multi-scale distribution of thermal properties of the rock massif was developed. Gneisses and dolerites differ significantly in thermal conductivity, volumetric heat capacity, degree of thermal anisotropy, and thermal expansion. Regularities in variations of rock thermal conductivity and volumetric heat capacity within a temperature range of 5–200 °C were characterized. Published dependences of thermal conductivity with Young's modulus and P-wave velocity in gneisses were refined. For the first time, the uncertainty in the results of measurements of thermal properties caused by rock heterogeneity and anisotropy was quantified. [ABSTRACT FROM AUTHOR]

The extraction-pyrolytic method of applying a TiO film coating has been considered. The coating is suitable for various applications, in particular as a coating for self-cleaning glass, photocatalytic sterilization for medical and microbiological purposes, solar energy, and automotive and construction industries. Advantages of this method are its low cost and the possibility of coating large surfaces. The processes of extraction of titanium(IV), application of films of organic extracts to substrates, and pyrolytic treatment of precursors have been described. The phase composition and microstructure of the coatings obtained have been studied. It has been shown that the application of solutions of organic extracts to glass and metal substrates contributes to the formation of nanostructured continuous films, which possess photocatalytic activity. [ABSTRACT FROM AUTHOR]

The characteristic details of the carbothermal synthesis of TiB powders from the stoichiometric mixture TiO-HBO-C at temperatures lower 1700 K are investigated using thermal analysis (ТG-thermogravimetry and DSC-differential scanning calorimetry), as well as X-ray diffraction and scanning electron microscopy. In the temperature interval 300 K → 1673 K → 1273 K and at a heating rate of 10 K/min, the reaction in the powder mixture begins at approximately 1300 K and ends at 1470 K during cooling. After 3 h of isothermal synthesis at 1473 K, the TiB yield is more than 90%. The resulting products are hexagonal plate-like crystals 5-10 μm across with thickness of 3 to 4 μm. Kinetic analysis showed that in the temperature range of 1330 to 1673 K the TiB synthesis reaction is of the first-order, and the calculated activation energy of the process is 315 ± 24 kJ/mol. [ABSTRACT FROM AUTHOR]

A technique for the formation of Ir and Ir—Pd nanoparticles on carbon nanotubes (CNTs) under hydrothermal conditions was proposed. Reduction of potassium hexachloroiridate(IV) from aqueous solutions with sodium tetrahydroborate in alkaline media at a temperature of 180 °C leads to the formation of iridium nanoparticles on the carbon material. Subsequently, the composite material Ir/CNT was modified by palladium deposition through the decomposition of an alkaline solution of tetraamminepalladium(II) chloride in an autoclave. The composition, dimensions, and structure of the obtained functional materials were characterized by scanning electron microscopy with local energy-dispersive X-ray fluorescence analysis, powder X-ray diffraction, and X-ray photoelectron spectroscopy. The metal particles uniformly coat on the CNTs and have diameters of 5–8 and 15–20 nm in the case of iridium and palladium, respectively. [ABSTRACT FROM AUTHOR]

The oxidation kinetics of TiB powders in air at temperatures up to 1,673 K was investigated using thermal analysis [thermogravimetry and differential scanning calorimetry (DSC)]. DSC-curves had three well distinguishable exo-effects in the temperature ranges of about 760-780, 960-980 and 1,630-1,650 K and a slightly lower intensity in the temperature range 1,000-1,600 K. With the temperature (T) and conversion fraction (α) increasing, the thickness of a scale, its composition and microstructure continuously changed. This led to a change in the limiting-rate step mechanism of the oxygen diffusion transport to the diboride-scale boundary. The powders oxidation macro-mechanism is slightly dependent on their dispersion and morphology, but these factors substantially influence the kinetics. It has been determined that the reaction is of the first formal order. The activation energy is 300-390 kJ/mol at low temperatures and α ≤5-7 % in the beginning of the reaction. In the end of the reaction the activation energy is ~20 kJ/mol, when T and α are high. [ABSTRACT FROM AUTHOR]

We have synthesized composite materials based on SBA-15 mesoporous silica and zirconium phosphate. The materials have been characterized by scanning electron microscopy, transmission electron microscopy, inductively coupled plasma mass spectrometry, X-ray diffraction, BET measurements, P NMR spectroscopy, and thermogravimetry, and have been employed as catalysts for ethanol dehydration. Even though their catalytic activity is somewhat lower than that of fine-particle zirconium phosphates with layered and framework structures, they offer an increased ethylene yield at low temperatures. [ABSTRACT FROM AUTHOR]

The synthesis and physical-chemical characteristics of sorbents based on mesoporous silicates MCM-41 and SBA-15 with grafted sulfide functional groups are described. Similar experiments were performed on silica gels for the comparison. For the above materials, the X-ray and texture characteristics before and after functionalization, as well as the grafted groups content and the sorption parameters of sorbents, have been determined using physical-chemical methods. The effect of the different conditions of the modification process on the grafting density of sulfide groups has been investigated. The evaluation of the sorption capacity of the obtained materials with respect to Pd(II) ions has been performed: the capacity is around 0.55 mmol/g, the recovery degree is 98-99% and the distribution coefficient is 26000 cm/g. [ABSTRACT FROM AUTHOR]

Possibility is considered of obtaining multicomponent oxide systems as afterburning catalysts for automobiles by flame-electrolytic oxidation and impregnation of oxide structures on aluminum. [ABSTRACT FROM AUTHOR]

This paper examines processes for the preparation of metallic iridium nanoparticles under hydrothermal conditions. The reduction of aqueous potassium hexachloroiridate(IV) solutions with sodium tetrahydridoborate in acidic and alkaline media at temperatures from 130 to 180°C has been shown to take 2–30 min and result in the formation of fine metallic iridium powder with a characteristic mosaic structure. The average size of the iridium(0) nanoparticles varies from 8 to 300 nm, depending on synthesis conditions, and the crystallite size is no greater than 10 nm. According to low-temperature nitrogen gas adsorption measurements, the specific surface area of the materials prepared in acid solutions ranges from 1 to 10 m2/g, and that of the materials prepared in alkaline solutions reaches 25 m2/g. X-ray photoelectron spectroscopy results demonstrate that the surface of the 8-nm-diameter iridium nanoparticles is covered with an oxide film. As shown by differential scanning calorimetry and thermogravimetry in an argon atmosphere, the fraction of iridium oxide compounds in the material with a specific surface area of 25 m2/g does not exceed 5 wt %. [ABSTRACT FROM AUTHOR]

This paper reports studies of thin films of nickel oxide obtained by the extraction–pyrolysis method on glass and quartz substrates at temperatures of 380–600°C. The films have been characterized by atomic force microscopy and X-ray diffraction. It is shown that amorphous and crystalline nickel oxide films are formed on the glass. The grain size depends on the annealing temperature, while increased annealing temperatures lead to recrystallization and a decrease in the grain size in NiO films from 130 to 35 nm. [ABSTRACT FROM AUTHOR]

Seven new phases containing hexachloroplatinate [PtCl6]2− and trans-1,2-dl-diammoniumcyclohexane 1,2-C6H10NH322+ ions were obtained by crystallization from solutions with minor variation of synthesis conditions. The compounds can be applied as precursors for the synthesis of effective anticancer drug tetraplatin ([PtC6H10(NH2)2Cl4]). The phase diversity was achieved by alterations including solvent acidity, crystallization rate, temperature, type of solvent, and the reagents ratio. The compounds were characterized by chemical and thermal analysis, IR, and 1H NMR spectroscopy. Crystal structures of the five compounds were determined by X-ray powder diffraction technique. The phases have ionic structures involving H2O, HCl molecules, or Cl− ions as supplementary species in the lattices. It helps to arrange some frames additionally interconnected by hydrogen bonds between ions and solvent molecules. It was suggested that crystal lattices adapted associated particles presented in solutions. It results in observed variety of the crystal structures. Besides the basic interest the obtained results are important for tetraplatin synthesis control. [ABSTRACT FROM AUTHOR]

Mesostructured carbon materials for electrodes of electrochemical capacitors are synthesized by the method of template-assisted synthesis. To enhance their capacitance characteristics, their surface is chemically activated by etching in fused KOH and NaOH. The structure of materials is studied by the methods of X-ray diffraction and gas adsorption. Their electrochemical characteristics are studied within the composition of electrodes for electrochemical capacitors with aqueous and nonaqueous electrolytes by impedance spectroscopy. It is found that the chemical activation approximately doubles the carbon specific surface area (up to 1700 m/g), decreases the amount of the mesostructured phase, and leads to spatial disorientation of carbon rods. Moreover, the specific capacitance of mesoporous carbon materials increases from 90 to 160 F/g. An increase in the alkali concentration increases both the specific surface area of samples and their specific capacitance in aqueous and nonaqueous electrolytes, which correlates with the shift of the micropore-to-mesopore ratio of the carbon matrix to micropores. It is shown that the nature of metal hydroxide affects the structural parameters of activated carbon materials which determine the relationship between the specific capacitance and the polarization current. [ABSTRACT FROM AUTHOR]

Composite proton-conducting electrolytes are synthesized based on HSiWO · xHO, CsHSO, (CsHPO)(CsHSO) and mesoporous matrices SBA-15 and MCM-41 and their transport and structural characteristics are studied. Composites based on silicotungstic acid demonstrate the conductivity from ∼10 to 10 S/cm in the temperature range of 25-140°C at the increased partial pressure of water vapor. The conductivity of systems CsHSO-SBA-15 (at T = 140-200°C) and (CsHPO)(CsHSO)-SBA-15 (at T = 200-230°C) reaches 10 S/cm and is independent of humidity. The electrolytes studied are promising as proton-exchange membranes of fuel cells operating at low and medium temperatures. [ABSTRACT FROM AUTHOR]

For composite electrodes based on active carbon DCL Supra 30, ordered mesoporous carbon, and synthetic carbon material Sibunit, the electrical double layer capacitance is studied. The original carbon samples are characterized by the methods of gas adsorption, X-ray diffraction, and transmission electron microscopy. The mesoporous structure of the material synthesized by the template method provides the maximum rate of ion transport in pores and demonstrates an insignificant decrease in the specific capacitance (9.5% in an aqueous electrolyte and 1.1% in an nonaqueous electrolyte) with an increase in the polarizing current. [ABSTRACT FROM AUTHOR]

The structure of silicate material of the SBA-15 type has been studied under variable composition of a salt solution in synthesis. Ammonium and sodium chlorides, as well as ammonium fluoride, introduced into the composition of the reaction mixture both at the first stage of precipitation and at the second stage of the thermal treatment (TT), have been used as the salt additives. The mesostructure was controlled by X-ray diffraction, gas adsorption and transmission electron microscopy. It was found that the multiple increase of the ionic strength of the solutions in the presence of chloride salts disrupt the stoichiometry of the silicate-surfactant interaction at the first stage of formation of mesostructure and leads to the formation of an impurity of irregular structure. The ions of ammonium promote an increase in the microporosity of the silicate wall. The presence of sodium ions reduces microporosity. Small quantities of fluoride ions (F: Si = 0.032) improve the ordering of the product at the stage of primary precipitation. At the ratio F: Si = 0.16, the hexagonal mesostructure is not formed. The introduction of fluorides at the TT stage leads to a decrease of the silicate pore wall thickness, microporosity and hexagonality of the pore. [ABSTRACT FROM AUTHOR]

Mesostructured carbon has been obtained by template synthesis. SBA-15 mesostructured silicate has been used as a template. The effect of the properties of a template on the ordering of a replica has been studied. It has been shown with the use of X-ray diffraction, gas adsorption, and electron microscopy that there are evident correlations of the conditions of synthesis of a template with the ordering of a carbon replica, which can be guided by the synthesis of materials. The ordering of a replica significantly depends on the mesopore volume of the initial template and thickness of the pore wall. One should use templates with the highest possible mesopore volume and minimal wall thickness to obtain highly ordered replicas. These templates can be prepared during the treatment of synthesized materials at temperatures close to 100°C. It has been determined that, when there is SBA-15, the presence of micropores is a necessary condition for the preparation of carbon replicas that retain the structure of the template. [ABSTRACT FROM AUTHOR]

A letter to the editor about a procedure for the preparation of trans-1,2-diaminocyclohexanetetrachloroplatinum (IV), a second generation antitumor drug, is presented.

Mesostructured silicate materials with different pore sizes and grafted sulfonic groups have been synthesized and characterized by thermal analysis, IR spectroscopy, and impedance spectroscopy. The results indicate that the-SO3H groups in these materials dissociate to give proton hydrates. The low-temperature proton conductivity of these materials is 3 × 10−6 to 4.5 × 10−4 Sm/cm and drops notably upon dehydration. [ABSTRACT FROM AUTHOR]

The molar heat capacity of ScCuO has been determined at temperatures from 350 to 893 K using differential scanning calorimetry. The experimental C( T) data have been used to evaluate the thermodynamic functions of the double oxide. [ABSTRACT FROM AUTHOR]

The heat capacity of PbSnO was measured from 500 to 1000 K, and the results were used to evaluate the thermodynamic functions of solid PbSnO. [ABSTRACT FROM AUTHOR]