This study focuses on developing a heterophase process for synthesizing rare-earth zirconates, specifically R2Zr2O7 /R2O3·2ZrO2 (R = La, Sm, Gd, Dy). We investigated the sorption properties of low-hydrated zirconium hydroxide, a precursor for complex-oxide phases, towards rare-earth elements' ions (La, Sm, Gd, Dy). The results indicate that sorption by low-hydrated zirconium hydroxide is a multifaceted process, involving the incorporation of rare-earth cations into the pores of low-hydrated hydroxide and ion exchange. The paper details the synthesis of R2Zr2O7 /R2O3·2ZrO2 (R = La, Sm, Gd, Dy), considering both «light» and «heavy» elements. The process process involves the interaction between Zr(OH)3÷1O0.5÷1.5·(1.6÷2.6)H2O, low-hydrated zirconium hydroxide, and an aqueous solution of rare-earth acetate (С(La3+) = 0.155 mol/l, С(Sm3+) = 0.136 mol/l, С(Gd3+) = 0.141 mol/l, С(Dy3+) = 0.120 mol/l) followed by heat treatment. The resulting phases and their thermolysis products were analyzed using differential thermal analysis and X-ray phase analysis. Single-phase rare-earth zirconates R2Zr2O7 (R = La, Sm, Gd) and the Dy2O3·2ZrO2 solid solution were only obtained at 800 °С. The lattice parameters are calculated for each phase. Lanthanum, samarium, and gadolinium zirconates exibited a cubic pyrochlore structure (Fd3–m), while dysprosium displayed a fluorite structure (Fm3–m). The average particle size of all zirconates was 1.14 ± 0.02 μm.

Rhenium alkoxocomplexes (Re4O6(OMe)12) and Re4O6(OPri)10) were obtained by the anodic dissolution of rhenium. The complexes were studied using the IR spectrometry and Energy Dispersive Analysis. Bimetallic rhenium–nickel alkoxocomplexes (Re4 – xNixO6(OMe)12, Re4 – xNixO6(OPri)10) and rhenium–cobalt alkoxocomplexes (Re4 – xCoxO6(OMe)12, Re4 – xCoxO6(OPri)10) were synthesized of monometallic alkoxocomplexes and characterized using the IR spectrometry. It is shown that homogeneous bimetallic powder of Re0.79Ni0.21 alloy can be produced of rhenium–nickel methylate and isopropylate and the powder of Re0.67Co0.33 alloy, of rhenium–cobalt methylate using the reduction in the hydrogen atmosphere at a temperature of 650°C and a pressure of 5 atm.

Objectives. To identify the regularities of electrochemical processing of the heat-resistant GS32-VI alloy in a sulfuric acid electrolyte with a concentration of 100 g/dm3 under the action of a pulsed current in a pulsed mode.Methods. Using the electrochemical technological complex EHK-1012 (developed by IP Tetran) and a non-compensatory method of measuring potential, polarization and depolarization curves with a change in pulse duration and a pause between them were recorded. The current pulses had an amplitude ranging from 0 to 3.5 A (when recording the polarization and depolarization curves), pulse durations ranging from 200 to 1200 ms, and a pause (delay) between pulses ranging from 50 to 500 ms. There were no reverse current pulses.Results. The parameters of the current program that provide the maximum values of the alloy dissolution rate and current output were determined: with a current pulse amplitude of 2 A, a current pulse duration of 500 ms, and a pause duration between pulses of 250 ms, the maximum dissolution rate of the alloy is 0.048 g/h·cm2, while the current output for nickel is 61.6% with an anode area of 10 cm2. The basic technological scheme for processing the heat-resistant GS32-VI alloy, which includes anodic alloy dissolution in a pulsed mode, is proposed.Conclusions. Electrochemical dissolution of GS32-VI alloy under pulsed current action results in an optimal dissolution rate ratio of the alloy components, ensuring the production of a cathode precipitate with a total nickel and cobalt content of 97.5%.

Objectives. To develop physical and chemical bases and methods to obtain rhenium–ruthenium isoproxide Re4-yRuyO6(OPri)10 —a precursor for obtaining a high-temperature alloy—from ruthenium acetylacetonate and rhenium isoproxide acquired by electrochemical methods.Methods. IR spectroscopy (EQUINOX 55 Bruker, Germany), X-ray phase and elemental analyses, energy-dispersive microanalysis (EDMA, SEM JSM5910-LV, analytical system AZTEC), powder X-ray diffraction (diffractometer D8 Advance Bruker, Germany), experimental station XSA beamline at the Kurchatov Synchrotron Radiation Source.Results. The isoproxide complex of rhenium–ruthenium Re4-yRuyO6(OPri)10 was obtained, and its composition and structure were established. Previously conducted quantum chemical calculations on the possibility of replacing rhenium atoms with ruthenium atoms in the isopropylate complex were experimentally proven, and the influence of the electroconductive additive on the composition of the obtained alloy was revealed.Conclusions. Physical and chemical bases and methods for obtaining rhenium–ruthenium isoproxide Re4-yRuyO6(OPri)10 were developed. The possibility of using rhenium–ruthenium Re4-yRuyO6(OPri)10 as a precursor in the production of ultra- and nanodisperse rhenium–ruthenium alloy powders at a record low temperature of 650°C were shown.

Objectives. The present study aims to develop new methods for the synthesis of molybdenum(VI) oxide, which is a precursor for the synthesis of functional materials, as well as to investigate the physicochemical properties of the resulting oxide phases. Methods. The synthesized phases and the products of their thermolysis were studied by differential thermal analysis, IR spectroscopy, X-ray diffraction analysis, and granulometry. Results. Three methods for the synthesis of molybdenum(VI) oxide were developed, and the physicochemical properties of the oxide phases obtained were studied. The first method consisted in the reaction of molybdenum pentachloride with a 6.0–9.5 mol/L ammonia solution, the second one was the reaction of niobium pentachloride with a sulfuric acid solution, and the third method involved the reaction of ammonium molybdate with nitric acid, affording brown molybdenum(V) MoO(OH)3 hydroxide, a bright blue precipitate of molybdenum blue MoO2.75, and white hydrated oxide MoO3·H2O, respectively. Conclusions. A series of thermal and X-ray diffraction analysis demonstrated that in all cases the samples were amorphous phases. Heat treatment at 580 °C of the synthesized phases led to the formation of a rhombic modification of molybdenum trioxide. The lattice parameters and X-ray density were calculated for all thermolysis products. The effect of heat treatment on the particle size of the synthesized samples and their thermolysis products was studied. Particle size analysis demonstrated that particles of different diameters were formed depending on the synthetic method. The smallest particle size (0.3–0.6 µm) was found in molybdenum trioxide, a product of the thermolysis of the sample obtained by the reaction of molybdenum pentachloride with a concentrated ammonium solution.

The thermal decomposition of acidic cobalt carboxylates (ACCs) with unsaturated carboxylic anions has been studied by TG/DTA in combination with DSC and mass spectrometry of gaseous thermolysis products. The temperature ranges of the main ACC thermal decomposition stages have been determined as (1) 50–225°С for dehydration (2) 210–450°C for dehydrated carboxylate polymerization, and (3) 370–500°C for decarboxylation. It has been concluded that the listed stages may superimpose on one another and occur simultaneously.

A method for the synthesis of mono- and bimetallic zirconium and/or hafnium oxides by supercritical antisolvent precipitation has been developed. The oxides have been obtained using a laboratory dispersing system, alkoxides (zirconium propoxide, hafnium butoxide) and zirconium acetylacetonate have been used as precursors. A white powder of amorphous phase with composition MO2 · mH2O · nCxHyOz (M = Zr, Hf) has been obtained in all experiments. Differential thermal and X-ray powder diffraction analysis have been used to study the obtained phases and their thermolysis products (mono- and bimetallic zirconium and/or hafnium dioxides). Particle size and their morphology have been studied by optical and electron microscopy and dynamic light scattering. It has been shown that the particles of prepared oxides have spherical shape, while their size is dependent on the molar ratio of initial solution components. According to electron microscopy data, annealed samples have smaller particle size as compared with the initial samples.

Cobalt(II) salts are synthesized from saturated monocarboxylic acids: formic, butyric, valerianic, caproic, enanthic, and caprylic acids. The resulting compounds are characterized by elemental analysis, IR spectroscopy, thermogravimetry, and differential scanning calorimetry. As a result of the thermal decomposition of the synthesized carboxylates and cobalt acetate, cobalt-containing nanocomposites are obtained. The obtained nanocomposites are studied by elemental analysis, IR spectroscopy, scanning and transmission electron microscopy, energy dispersive X-ray spectroscopy, and X-ray phase analysis. Magnetic studies of the obtained nanocomposites are carried out.

— Using high-pressure, high-temperature processing of a low water content amorphous tantalum hydroxide, TaO 0.5–2.0 (OH) 4–1 · (1.0–2.5)H 2 O, at p = 5.0–6.0 GPa and t = 800–900°C, we have obtained a mixture of two phases, Ta 2 O 5 · 2/3H 2 O (sp. gr. P 6 3 / mсm , а = 7.4736(2) Å, с = 7.6798(2) Å, Z = 3, V = 371.48(1) Å 3 ) and H 2 Ta 2 O 6 · 2/3H 2 O (sp. gr. P 6 3 / mсm , а = 7.4998(2) Å, с = 7.6171(2) Å, Z = 3, V = 371.04(1) Å 3 ), both crystallizing in the hexagonal tungsten bronze (HTB) structure. According to thermogravimetric analysis results, the material contains 4.9(3)% water. After water removal, heating in air to 550°C causes the HTB phase to convert into δ-Ta 2 O 5 . X-ray diffraction data have been analyzed by the Rietveld method and the following reliability factors have been obtained: R F = 0.0374 for Ta 2 O 5 · 2/3H 2 O and R F = 0.0416 for H 2 Ta 2 O 6 · 2/3H 2 O. We assume that the MO 3 stoichiometry of the basic HTB cell in these compounds is ensured by different mechanisms.

Experimental-statistical mathematical models are built for nickel itaconate thermolysis to relate some response functions (carbon, hydrogen, oxygen, and nickel concentrations in the nanocomposite, yield of the nanocomposite, contents of β-nickel and nickel oxide phases, and nanoparticle diameter) to the thermolysis temperature and time. Response surfaces are constructed to illustrate the dependence of the above-listed response functions on the thermolysis temperature and time. These response functions are analyzed to determine the synthetic parameters that would provide the preparation of nanocomposites with tailored characteristics, in particular, with the highest content of the magnetoactive β-nickel phase.

Using high-pressure, high-temperature processing of a low water content amorphous tantalum hydroxide, TaO0.5–2.0(OH)4–1 · (1.0–2.5)H2O, at p = 5.0–6.0 GPa and t = 800–900°C, we have obtained a mixture of two phases, Ta2O5 · 2/3H2O (sp. gr. P63/mсm, а = 7.4736(2) Å, с = 7.6798(2) Å, Z = 3, V = 371.48(1) Å3) and H2Ta2O6 · 2/3H2O (sp. gr. P63/mсm, а = 7.4998(2) Å, с = 7.6171(2) Å, Z = 3, V = 371.04(1) Å3), both crystallizing in the hexagonal tungsten bronze (HTB) structure. According to thermogravimetric analysis results, the material contains 4.9(3)% water. After water removal, heating in air to 550°C causes the HTB phase to convert into δ-Ta2O5. X-ray diffraction data have been analyzed by the Rietveld method and the following reliability factors have been obtained: RF = 0.0374 for Ta2O5 · 2/3H2O and RF = 0.0416 for H2Ta2O6 · 2/3H2O. We assume that the MO3 stoichiometry of the basic HTB cell in these compounds is ensured by different mechanisms.

Currently, various amino bisphosphonates are widely used in the treatment of many bone diseases. One of the most well-known complex compounds of neridronic acid (6-amino-1-hydroxyhexylidene-1,1- bisphosphonic acid) is sodium neridronate – a bisphosphonate, which is used to treat osteogenesis and Paget's disease. However, there is no data on compounds of neridronic acid with rare earth elements. A new complex of lanthanum with 6-amino-1-hydroxyhexylidene-1,1-bisphosphonic acid (I) was obtained and characterized by various physicochemical methods (chemical analysis, IR spectroscopy, solid-phase 31P NMR spectroscopy, optical microscopy, PCA, DTA). According to the research data the complex I has the composition {La[(H3N-(CH2)5-C(OH)(PO2(OH))2]2(H2O)2}[OH]·H2O and represents the coordination 1D-polymer due to two bridged phosphonic groups with lanthanum atoms in a tetragonal-antiprismatic environment. In a crystal, polymer chains form a 3D-frame porous structure by means of strong hydrogen bonds O─H ··· O and N─H ··· O with endless channels, available to include a variety of inorganic anions or small organic molecules. A study under the microscope showed that the sample is needle crystals (thin rods) of different lengths. The particle size distribution was obtained by laser diffraction, and the average particle size was determined: 50 µm in length and 2.5 µm in thickness.

The article is devoted to the substantiation of the proposed technological scheme of electrochemical processing of rhenium-containing heat-resistant alloy ZhS32-VI of composition (mass %): Re - 4.0; Co - 9.3; W - 8.6; Y - 0.005; Lа - 0.005; Al - 6.0; Cr - 5.0; Tа - 4.0; Nb - 1.6; Mо - 1.1; С - 0.16; B - 0.15; Cе - 0.025, Ni - 60.05 to obtain nickel-containing cathode deposits. The results of studying the composition, surface morphology and granulometric analysis of cathodic precipitates obtained during the electrochemical processing of the spent heat-resistant alloy ZhS32-VI with the use of acid electrolytes are presented. Anodic dissolution of ZhS32-VI was performed in the galvanostatic mode. The effect of the electrolyte composition on the process parameters (current yield, distribution of alloy components between the electrolysis products, particle size distribution of the cathode product), electrochemical processing of this alloy were established. It is shown that depending on the nature of the electrolyte, cathode deposits of different chemical and phase composition can be obtained. They differ in the size and morphology of the surface. It has been established that the value of the cathode precipitate grains obtained in acid electrolytes is almost the same: 99% of the cathode precipitate grains are in the range from 0.04 to 0.60 μm. The main difference is a slight increase in the amount of fine fraction when sulphosalicylic acid is added to the electrolyte. All the cathodic deposits obtained have a dendritic structure, the development of which depends on the nature of the electrolyte, the precipitates obtained with the use of a nitrate electrolyte having the most developed structure and the smallest particle size.

Multiple regression equations linking properties of nanocomposites synthesized by thermolysis of unsaturated nickel dicarboxylates in an argon medium and magnetic characteristics have been obtained by processing experimental data. The equations obtained enable one to predict the magnetic characteristics on the basis of data on the phase composition of the nanocomposite, the content of nickel, and average diameter of nickel-containing nanoparticles; moreover, information on the effect of characteristics on the magnetic properties can be obtained.

The heteromolecular insertion of carbon dioxide in combination with heterocumulenes, iso(thio)cyanates or N,N′ -dicyclohexylcarbodiimide, into rhenium–alkoxy group bond was accomplished for the first time in relation to reactivity of rhenium oxoalkoxides. The ease of combined insertion of iso(thio)cyanate and carbon dioxide into Re–O(Me) bond is determined by the nature of the heterocumulene organic group. Indeed, if ethyl iso(thio)cyanate is used in the reaction, the insertion is reversible, whereas the reaction with PhNCS (unlike PhNCO) together with carbon dioxide leads to complete insertion into two Re–O(R) bonds to give the insertion product (OMe) 10 O 6 Re 4 [OC(O){N(Ph)C(S)} 2 -OMe] 2 . In similar reactions carried out with N,N′ -dicyclohexylcarbodiimide, a dependence of the number of bonds participating in the inner-sphere condensation of the inserted moieties on the duration of the experiment was found for the first time. An increase in the time of synthesis from 3 to 5 h results in insertion involving six rather than three bonds, the heteromolecular insertion products being (OMe),O 6 Re 4 {OC(O)[(Hex)N=C=N(Hex)] 2 } 3 and (OMe) 6 O 6 Re 4 {OC(O)[(Hex)N=C=N(Hex)] 2 } 6 , respectively.

Quantum-chemical calculations of the structure and relative thermodynamic stability of tetranuclear clusters M x N 4 – x O 6 (OMе) 10 (M, N = Re, Ru; x = 4–0) including geometric isomers of bimetallic clusters are performed to establish the possibility of replacing Re atoms by Ru atoms while maintaining a cyclic tetranuclear structure. As the initial model, the structure of Re 4 O 6 (OPri) 10 was chosen which is an almost regular rhombus. The values of the metal–metal and metal–oxygen interatomic distances are calculated, and features of their variation under the transition from mononuclear to heteronuclear clusters and from neutral clusters to anions are discussed. Differences between the relative thermodynamic stability of homometallic and heterometallic tetranuclear clusters, including the geometric isomers of the latter, are discussed.