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We have synthesized highly anisotropic plate-like nanoparticles of aluminum-substituted strontium hexaferrite via the crystallization of 4Na2O × 9SrO × 5.5Fe2O3 × 4.5Al2O3 × 4B2O3 glass, achieving tunable sizes by adjusting the annealing temperature (650–750 °C). Particle sizes range from 39 nm × 4.5 nm to 90 nm × 7.1 nm. Aluminum substitution significantly increases the coercivity of the colloid particles up to 5600 Oe. These nanoparticles form stable aqueous colloids in the pH range of 2–4. The ferrofluids exhibit a strong "jalousie effect" of adjustable optical transmission in external magnetic fields. The transmission difference rises with increasing nanoplate diameter and anisotropy factor. The high remanence of the hexaferrite particles allows them to be manipulated by weak magnetic fields, providing high-frequency particle motion with available electromagnets. Tunable particle sizes facilitate specific applications: smaller particles offer higher relaxation frequencies and better stability, while larger particles provide superior light scattering and induced mechanical momentum. These properties make the nanoparticles suitable for microfluidic stirring, mechanical impacting for cancer treatment, high-frequency light modulation, optical probing of magnetic fields, and micrometer-scale viscoelasticity sensing. [ABSTRACT FROM AUTHOR]

New bifunctional cobalt catalysts for combined Fischer–Tropsch synthesis and hydroprocessing of hydrocarbons containing Pt were developed. To prepare catalysts in the form of a composite mixture, the FT synthesis catalyst Co-Al2O3/SiO2 and ZSM-5 zeolite in the H-form were used as metal and acid components, respectively, with boehmite as a binder. The catalysts were characterized by various methods, such as XRD using synchrotron radiation, SEM, EDS, TEM and TPR. The effect of the Pt introduction method on the particle size and conditions for cobalt reduction was studied. The testing of catalysts in Fischer–Tropsch synthesis was carried out at a pressure of 2.0 MPa, a temperature of 240 and 250 °C, an H2/CO ratio of 2 and a synthesis gas volumetric velocity of 1000 h−1. It is shown that the method of introducing a hydrogenating metal by adjusting the nano-sized spatial structure of the catalyst determined the activity in the synthesis and group and fractional composition of the resulting products. It is established that the presence of Pt intensified the processes of synthesis and hydrogenation, including isomeric products, and reduced the content of unsaturated hydrocarbons. The application of Pt by impregnation onto the surface of the metal component of the catalysts provided the highest productivity for C5+ hydrocarbons, and for the acidic component, it enabled maximum cracking and isomerizing abilities. [ABSTRACT FROM AUTHOR]

This article reports on a simple method for producing high-octane gasoline from CO and H2 on a Co-Al2O3/SiO2/HZSM-5/Al2O3 hybrid catalyst. In the selected pressure range (0.5, 1.0, and 2.0 MPa), it was found that a decrease in pressure and an increase in temperature contribute to an increase in the content of branched hydrocarbons. The optimal technological parameters of the process were determined to ensure high selectivity and productivity for C5–C10 hydrocarbons: pressure—1.0 MPa, ratio H2/CO = 2, gas space velocity—1000 h−1, temperature—250 °C. The selectivity for the gasoline fraction is 65.2%, and the ratio of branched to linear hydrocarbons (iso/n index) is 2.3. Under the specified technological conditions, an experimental batch of gasoline fraction (1000 cm3) was produced at the pilot plant during 400 h of continuous operation. The main physicochemical and operational parameters of the experimental gasoline fraction of hydrocarbons have been determined. The octane number determined by the research method according to GOST R 52947-2019 is 78.5 units. [ABSTRACT FROM AUTHOR]

Crystal structures of high-temperature t- (LaF3-type) and low-temperature β- (β-YF3-type) modifications of 61(58Ce0.564Gd0.5)F3 – "pseudo61PmF3" near the temperature of a polymorphic transformation (PolTr) (−148 ± 5 °C) were studied by in situ X-ray diffraction (XRD). During the t- → β- "pseudo61PmF3" PolTr (at cooling) anions are ordered in the direction perpendicular to the hexagonal close packing (HCP) layers. This is accompanied by 13% stretching of the t-type crystal lattice in the <010> direction and compression in the <100> (0.8%) and <001> (0.9%) directions. The structural changes in t- and β- "pseudo61PmF3" at heating from −148 to +20 °C represent changes (decrease and increase) in cation–anion bond lengths (BL) without changing the shape of the coordination polyhedron (CP). "Pseudo61PmF3" is a material with giant negative thermal expansion at PolTr (NTE-II). The decrease in volume during the β- → t- "pseudo61PmF3" PolTr (at heating) is 3.8%. [ABSTRACT FROM AUTHOR]

Fast crystallization of the monoclathrochelate cobalt(II) intracomplex [Co(Cl2Gm)3(BAd)2] (where Cl2Gm2− is a dichloroglyoxime dianion and BAd is an adamantylboron capping group, 1), initially obtained by the direct template condensation of the corresponding chelating α-dioximate and cross-linking ligand synthons on the Co2+ ion as a matrix, from benzene or dichloromethane afforded its structural triclinic and hexagonal polymorphs. Its prolonged recrystallization from dichloromethane under air atmosphere and sunlight irradiation unexpectedly gave the crystals of the CoIIICoIICoIII-trinuclear dodecachloro-bis-clathrochelate intracomplex [[CoIII(Cl2Gm)3(BAd)]2CoII] (2), the molecule of which consists of two macrobicyclic frameworks with encapsulated low-spin (LS) Co3+ ions, which are cross-linked by a μ3-bridging Co2+ ion as a bifunctional Lewis-acidic center. The most plausible pathway of such a 1 → 2 transformation is based on the photoinitiated radical oxidation of dichloromethane with air oxygen giving the reactive species. Cobalt(II) monoclathrochelate 1 was found to undergo a temperature-induced spin crossover (SCO) both in its solutions and in the solid state. In spite of the conformational rigidity of the corresponding quasiaromatic diboron-capped tris-α-dioximate framework, the main parameters of this SCO transition (i.e., its completeness and gradual character) are strongly affected by the nature of the used solvent (in the case of its solutions) and by the structural polymorphism of its crystals (in the solid state). In the latter case, the LS state (S = 1/2) of this complex is more thermally stable and, therefore, the cobalt(II)-centered 1/2 → 3/2 SCO is more gradual than that in solutions. [ABSTRACT FROM AUTHOR]

A new 1D-coordination polymer [Co(Piv)2(NH2(CH2)6NH2)]n (1, Piv is Me3CCO2− anion) was obtained, the mononuclear fragments {Co(O2CR)2} within which are linked by μ-bridged molecules of hexamethylenediamine (NH2(CH2)6NH2). For this compound, two different monoclinic C2/c (α-1) and P2/n (β-1) phases were found at room temperature by single-crystal X-ray diffraction analysis, with a similar structure of chains and their packages in unit cells. The low-temperature phase (γ-1) of crystal 1 at 150 K corresponds to the triclinic space group P-1. As the temperature decreases, the structural phase transition (SPT) in the α-1 and β-1 crystals is accompanied by an increase in the crystal packing density caused by the rearrangements of both H-bonds and the nearest ligand environment of the cobalt atom ("octahedral CoN2O4 around the metal center at room temperature" → "pseudo-tetrahedral CoN2O2 at 150 K"). The SPT was confirmed by DSC in the temperature range 210–150 K; when heated above 220 K, anomalies in the behavior of the heat flow are observed, which may be associated with the reversibility of SPT; endo effects are observed up to 300 K. The SPT starts below 200 K. At 100 K, a mixture of phases was found in sample 1: 27% α-1 phase, 61% γ-1 phase. In addition, at 100 K, 12% of the new δ-1 phase was detected, which was identified from the diffraction pattern at 260 K upon subsequent heating: the a,b,c-parameters and unit cell volume are close to the structure parameters of γ-1, and the values of the α,β,γ-angles are significantly different. Further heating leads to a phase transition from δ-1 to α-1, which both coexist at room temperature. According to the DC magnetometry data, during cooling and heating, the χMT(T) curves for 1 form a hysteresis loop with ~110 K, in which the difference in the χMT values reaches 9%. Ab initio calculations of the electronic structure of cobalt(II) in α-1 and γ-1 have been performed. Based on the EPR data at 10 K and the ab initio calculations, the behavior of the χMT(T) curve for 1 was simulated in the temperature range of 2–150 K. It was found that 1 exhibits slow magnetic relaxation in a field of 1000 Oe. [ABSTRACT FROM AUTHOR]

The results of detailed characterization of new antimicrobial materials in the form of Ce(NO3)3 × 6H2O salt with the proposed crystal-chemical composition of [Ce3+(H2O)4(NO3)3] × 2H2O and its aqueous solution by X-ray diffraction (XRD), differential scanning calorimetry (DSC), X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS) are presented. The stages of [Ce3+(H2O)4(NO3)3] × 2H2O thermal decomposition with the formation of [Ce3+(H2O)4(NO3)3] (<220 °C), Ce3+ONO3 (230–320 °C) and Ce4+O2 (>300 °C) are shown. It was found that Ce3+ ions in the composition of [Ce(H2O)4(NO3)3] × 2H2O salt and in its aqueous solution retain their formal charge (FC Ce = 3) and coordination number (CNCe = 10, where 6O from three NO3− groups and 4O from four 4H2O molecules) with the reorientation of nitro groups in Ce3+ far environment in an aqueous salt solution. It was established that [Ce3+(H2O)4(NO3)3] × 2H2O, [Ce3+(H2O)4(NO3)3] and Ce3+ONO3 salts inhibit the growth of Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa bacteria in the absence of radiation with a growth zone inhibition diameter D > 37 mm with Dmax = 45 mm on the multiphase sample ([Ce3+(H2O)4(NO3)3], Ce3+ONO3, Ce4+O2), which is higher than that on penicillin (D = 12–18 mm). It is shown that an increase in the [Ce3+(H2O)4(NO3)3] × 2H2O salt concentration in an aqueous solution has a positive effect on antimicrobial activity. It is not excluded that the absence of interaction of Ce3+ ions in the salt solution with Langmuir phospholipid monolayers of phosphatidylethanolamine (DPPE) and phosphatidylglycerin (DPPG) is associated with the damage to the protein component of the bacterial membrane and not with the phospholipid one and/or with the "penetration" of Ce3+ ions into the cell and violation of its water-ionic balance. It is shown that the "H-Beta – Ce3+(NO3)3 × 6H2O" system fabrication with biocompatible H-Beta zeolite contributes to the preservation of antimicrobial activity in the dark (Pseudomonas aeruginosa) with a decrease in the amount of the active component. [ABSTRACT FROM AUTHOR]

In order to clarify the role of R2O3 in the metal-oxide catalysts derived from complex oxide precursors, a series of R1.5Ca0.5NiO4 (R = Nd, Sm, Eu) complex oxides was obtained. A significant systematic increase in the orthorhombic distortion of the R1.5Ca0.5NiO4 structure (K2NiF4 type, Cmce) from Nd to Eu correlates with a corresponding decrease in their ionic radii. A reduction of R1.5Ca0.5NiO4 in the Ar/H2 gas mixture at 800 °C causes a formation of dense agglomerates of CaO and R2O3 coated with spherical 25–30 nm particles of Ni metal. The size of metal particles and oxide agglomerates is similar in all Ni/(R2O3,CaO) composites in the study. Their morphology is rather similar to the products of redox exsolution obtained by the partial reduction of complex oxides. All obtained composites demonstrated a significant catalytic activity in the dry reforming (DRM) and partial oxidation (POM) of methane at 700–800 °C. A systematic decrease in the DRM catalytic activity of composites from Nd to Eu could be attributed to the basicity reduction of R2O3 components of the composite catalysts. The maximum CH4 conversion in POM reaction was observed for Ni/(Sm2O3,CaO), while the maximum selectivity was demonstrated by Nd2O3-based composite. The possible reasons for the observed difference are discussed. [ABSTRACT FROM AUTHOR]

The effect of synthesis conditions on the features of the long- and short-range order of Ln 2 (WO 4 ) 3 (Ln = Gd, Dy, Ho, Yb) powders synthesized via coprecipitation of salts has been studied by a complex of physico-chemical techniques including synchrotron X-ray powder diffraction, X-ray absorption spectroscopy, Raman and infrared spectroscopy, and simultaneous thermal analysis. It was found that crystallization of amorphous precursors begins at 600 °C/3 h and leads to the formation of the monoclinic structure with sp. gr. C12/c1(15) for Ln 2 (WO 4 ) 3 (Ln = Gd, Dy) and with sp. gr. P12 1 /a1(14) for Ln = Yb, whereas crystallization of Ho precursor requires even higher temperature. After annealing at 1000 °C, the P12 1 /a1(14) phase becomes the dominant phase component for all heavy lanthanoid types except for Ln = Gd. It was shown that the Ln (Ln = Dy, Ho, and Yb) tungstates with the P12 1 /a1(14) monoclinic structure correspond to trihydrates Ln 2 (WO 4 ) 3 ·3H 2 O formed due to a rapid spontaneous hydration under ambient conditions. It was concluded that the proneness to hydration is due to a specific structure of the P12 1 /a1(14) phase with large voids available to water molecules. Modifications in the local structure of Ln-O coordination shell accompanying the structure type change and hydration are monitored using EXAFS spectroscopy. [ABSTRACT FROM AUTHOR]

Laser Ca3(VO4)2 single crystals (СVO; space group R3c, Z = 21) with crystallochemical formula Ca118Ca218Ca318Ca46(Ca5 + Са5А)3(V118V218V36)O168 grown by the Czochralski method were doped with Мn2O3 (CVO:Мn2O3) and Сo3O4 (CVO:Co3O4) by high-temperature diffusion annealing. Statistical and local structures were comprehensively studied by single-crystal and powder synchrotron X-ray diffraction and conventional single-crystal X-ray diffraction as well as by X-ray absorption spectroscopy for the first time. The presence of Mn(2+δ)+ ions with a mixed formal charge and Co2+ ions in the Ca2 (monocapped trigonal prism), Ca3 (two-capped trigonal prism), and Ca4 (octahedron) sites was revealed by diffraction methods. The tetrahedral coordination and the coordination intermediate between tetrahedral and octahedral were established for Mn(2+δ)+ and Co2+ ions, respectively. A fundamentally different structural behavior of dopant ions (concentration, formal charge, and coordination environment) in the CVO crystals doped with manganese in the form of Mn2O3 during the crystal growth or by high-temperature diffusion annealing was observed. The relationship between characteristic bands in the absorption, fluorescence, and excitation spectra of CVO:Мn2O3 and CVO:Co3O4 samples and transition metals with specific formal charges is discussed. [ABSTRACT FROM AUTHOR]