Russian Journal of Inorganic Chemistry最新文献

In this study, the complexation of silver(I) with azaheterocyclic ligands (bipy, phen) in the presence of perchlorinated borate anions, [B₁₀Cl₁₀]^2– and [B₁₂Cl₁₂]^2–, was investigated in acetonitrile. Complexes with the general formula [Ag₂L₄][B_nCl_n] (L = bipy, phen; n = 10, 12) were successfully isolated. The final compounds were characterized using elemental analysis and IR spectroscopy. The structures of the [Ag₂(bipy)₄][B_nCl_n] (n = 10, 12) complexes were elucidated via X-ray diffraction (CCDC nos. 2325088, 2358488). It was determined that the compounds consist of either a binuclear cationic silver(I) complex with azaheterocyclic ligands, [Ag₂(bipy)₄]²⁺, or two mononuclear complexes, {[Ag(bipy)₂]₂}²⁺, with the boron cluster anions forming the anionic part of both complexes. Additionally, weak argentophilic Ag…Ag interactions were observed within the structures.

The Cd²⁺ and K⁺ co-doped Y₂O₃:Yb³⁺/Er³⁺ upconversion phosphors were synthesized via the combustion route and analyzed for their crystal structure, spectroscopic properties, upconversion behavior, and optical thermometric capabilities. Powder X-ray diffraction analysis confirmed that the crystal structure of host remained intact, with varying lattice parameters observed: decreasing for lower concentrations of Cd²⁺ and K⁺ (1 mol %) and slightly increasing at 3 and 5 mol % doping. Scanning electron microscopy reveals the fine particulates of sizes around 100 nm in 5 mol % Cd²⁺ and K⁺ co-doped Y₂O₃:Yb³⁺/Er³⁺while without Cd²⁺ and K⁺co-doping, it shows agglomerated form with spherical and rod shaped particles.Spectroscopic analysis across the UV-visible-NIR spectral range (200–2000 nm) indicated that Cd²⁺ and K⁺ dopants did not alter the spectral characteristics of prepared upconversion phosphor Y₂O₃:Yb³⁺/Er³⁺. Under excitation of 980 and 932 nm diode lasers, the upconversion emission exhibited green and red bands attributed to Er³⁺ ions. The intensity of the red band was predominant under 980 nm excitation, whereas the green band showed higher emission intensities under 932 nm excitation. Cd²⁺ and K⁺ doping significantly influenced the emission intensities of both bands but did not affect the emission wavelengths, with intensities decreasing as dopant concentrations increased. The temperature-dependent upconversion emission intensity variation was studied for optical thermometric applications, revealing enhanced relative sensitivity in Cd²⁺ and K⁺ doped samples compared to undoped phosphor. The maximum relative sensitivity of 0.01455 K^–1 at 303.15 K has been achieved with the 5 mol % Cd²⁺ and K⁺ co-doped upconversion phosphor, suggesting its potential for optical thermometry. Furthermore, evaluation of CIE color coordinates derived from upconversion emission spectra showed that Cd²⁺ and K⁺ doping had negligible impact on color chromaticity.

MAX phases of various compositions have recently gained increasing attention due to their layered structure and the combination of properties typical of both ceramic materials and metals. Consequently, the development of scalable methods for synthesizing these compounds with enhanced phase purity is of significant importance. In this work, the effects of different parameters on the composition and properties of the Ti₂AlC MAX phase were investigated, particularly when using a protective salt melt (KBr as an example). The study focused on the ratios of the starting reagents (n(Ti) : n(Al) : n(C)), the temperature, and the duration of heat treatment. It was found that at 1100°C, the highest yield of Ti₂AlC (94.4%) was obtained with a molar ratio of n(Ti) : n(Al) : n(C) = 2 : 1.1 : 0.9. The results showed that varying the synthesis temperature between 900 and 1100°C had a minimal impact on the target MAX phase content (ranging from 94 to 96%), with the maximum Ti₂AlC content observed at 1000°C. Additionally, the influence of synthesis temperature (900, 1100, and 1200°C) on the microstructure, thermal behavior in an air flow, and the electron work function was also studied.

In this work, the pyrohydrolysis of β-AlF₃ and FeF₃ in Ar + 10 vol % H₂O with and without 20 vol % NH₃ were investigated using scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDS) and X-ray powder diffraction. The results indicate that β-AlF₃/FeF₃ absorbs NH₃ and H₂O to form NH₄AlF₄/NH₄FeF₄ at 150–300/150–250°C, respectively. No pyrohydrolysis of β-AlF₃ occurs at 350°C and β-AlF₃ transforms to α-AlF₃ at T ≥ 400°C under NH₃ + H₂O condition. Under the same condition, Fe₂O₃ with minor Fe₃O₄ form during the pyrohydrolysis of FeF₃ between 300–400°C, and the content of Fe₃O₄ increases with the increment of temperature. While pure finer Fe₂O₃ forms quickly during the pyrohydrolysis of FeF₃ in H₂O gas between 300–400°C. Based on the above results, the optimal pyrohydrolysis of FeF₃ to produce finer Fe₂O₃ was further analyzed.

This study aims to investigate the physicochemical properties of fertilizers containing sodium phosphate and sodium iodide salt. The research employs a hygrometric method to analyze properties of the NaI–NaH₂PO₄–H₂O ternary system at 298.15 K from dilution (0.2 mol kg^–1) to about saturated solution and for different ionic-strength fractions y of NaI (y = I_NaI/(({{I}_{{{text{Na}}{{{text{H}}}_{{text{2}}}}{text{P}}{{{text{O}}}_{{text{4}}}}}}}) + I_NaI)) with y = 1/4, 1/3, 1/2, 2/3, 3/4. The obtained data allow the deduction of diverse thermodynamic properties of the system (water activity, osmotic coefficient). Experimental results were compared with predictions from four models (Dinane’s ECA, Lin et al., Robinson and Stokes (RS) and Lietzke and Stoughton (LS II). Additionally, the Pitzer–Simonson–Clegg (PSC) model was used to correlate the data for determining binary and ternary interionic parameters for predicting solute activity coefficients of solutes and excess Gibbs energy G^ex of the NaH₂PO₄–NaI–H₂O at different compositions. This analysis enhances our understanding of the influence of NaI on phosphate-based fertilizer systems, offering crucial insights for developing fertilizers aimed at improving agricultural productivity and fostering sustainable farming practices.

Hollow aluminosilicate microspheres (cenospheres) of stabilized composition (glass phase, 95.4 wt %; (SiO₂/Al₂O₃)_glass, 3.1 wt %) isolated from coal combustion fly ashes were used to prepare composite sorbents containing a sorption-active component based on framework zirconosilicates. The synthesis products were characterized by X-ray powder diffraction (XRD), electron microscopy−energy-dispersive X-ray spectral analysis (SEM−EDX), and low-temperature nitrogen adsorption; their Cs⁺ sorption properties were studied. The prepared zirconosilicate material exhibits a high distribution coefficient in Cs⁺ sorption from aqueous solutions (ca. 10³–10⁴ mL/g) and a stable sorption capacity due to decationization. The usability of spark plasma sintering (SPS) technology to provide high-density mineral-like ceramics based on the zirconosilicate sorbent for cesium immobilization was investigated. Dilatometric, structural, and porosity analyses were performed for ceramics sintered at various temperatures (800–1000°C).

Polycrystalline samples of the pseudobinary system Ba₂YMoO₆–[Ba₂YCuO₅] were synthesized using the gel combustion method. The obtained samples were investigated using X-ray diffraction and photoluminescence spectroscopy. The substitution of Mo with Cu led to the stabilization of cubic phases Fm3̅m and F4̅3m of the solid solution Ba₂YMo_{1 – x}Cu_xO_{6 – δ} (0 ≤ x ≤ 0.5) in air.

Knowledge of the parameters and mechanisms of proton transfer from the medium to the macrocyclic ligand in complexes of highly substituted phthalocyanines is necessary for optimization of technological processes of catalysis and design of functional materials. Octakis(3,5-di-tert-butylphenoxy)phthalocyanine complexes with 3d-metal ions have been synthesized, and their acid–base reactions have been studied by UV-vis and ¹H NMR spectroscopy. The chemical structure of the complexes has been determined using elemental analysis, MALDI-TOF mass spectrometry, IR, ¹H NMR, and UV-vis spectroscopy data. Complete protonation of the Co, Ni, and Cu complexes takes place in dichloromethane–trifluoroacetic acid mixtures. Doubly and quadruply protonated forms have been identified in UV-vis spectra. The concentration ranges of existence, UV-vis parameters, and the thermodynamic stability constants of the protonated forms, as well as their relationship with the electronic structure of the coordination center, have been determined.

The isobaric heat capacity of magnesium praseodymium hexaaluminate PrMgAl₁₁O₁₉ having the magnetoplumbite structure was measured by three calorimetric methods in the temperature range 2–1865 K. Reconciled and smoothed heat capacity data were used to calculate thermodynamic functions (entropy, enthalpy change, and reduced Gibbs energy) in this temperature range. A gentle heat capacity anomaly with a peak at about 8 K was found; its entropy and enthalpy were calculated. Magnetic properties of PrMgAl₁₁O₁₉ were studied by dynamic magnetic susceptibility measurements in the range 2–300 K. The results of magnetic measurements revealed an anomaly on the imaginary component of dynamic magnetic susceptibility, the temperature range of which matched that of the heat capacity anomaly.

The high-entropy niobate (Mg_0.2Cu_0.2Ni_0.2Co_0.2Zn_0.2)Nb₂O₆ with a columbite structure has been synthesized for the first time by a modified solution combustion method followed by high-temperature sintering. According to the diffuse reflectance spectra, the direct band gap is 3.36 eV. The niobate is characterized by the mixed electronic–ionic conductivity (2.5 × 10^–3 S/cm at 750°С) comparable with the conductivity of columbite Mg_0.8Cu_0.2Nb₂O₆.