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Magnetic nanoparticles of magnetite structure were obtained by the aqueous chemical synthesis, namely: using the chemical co-precipitation from the 1:2 M ratio mix of the iron chlorides (II, III) water solution with the ammonia used as precipitation agent as well as with oleic acid. Obtained nanopowders were studied using the X-Ray diffraction, infrared spectroscopy, scanning and transmission electron microscopy, low-temperature nitrogen absorption, and small-angle X-Ray scattering methods in order to determine the influence of synthesis techniques (homogenization procedure, separation methods – decantation, vacuum filtration, rotary evaporation, or magnetic separation), on the phase composition, size, morphology and magnetic parameters of the nanoparticles. It was demonstrated that the value of the specific surface area of nanoparticles with the average size of 10–20 nm is relatively high (75–132 m2/g) and their shape is lamellar or rod-shaped as well as cylindrical (round). The technique of separating nanoparticles from the mother liquor had a dominant effect on the morphology of nanoparticles. Dynamic and Electrophoretic Light Scattering methods showed that homogenization procedure, separation methods and especially surface modification with oleic acid affect the size and surface charge of the nanopowders.

Structural analysis in the range of characteristic sizes from 1 nm to ~1.5 µm was performed for SiO2–TiO2 aerogels prepared in supercritical CO2, isopropanol, hexafluoroisopropanol, or methyl-tert-butyl ether using small-angle X-ray scattering and neutron scattering complementary methods. A two-level model that accounts for scattering by individual inhomogeneities and their aggregates, which have fractal properties, satisfactorily describes the aerogel structures over the entire range of scales. It is shown for the first time that the titania concentration is the key factor in the small-angle neutron and X-ray scattering by SiO2–TiO2 aerogels. The phase composition of an aerogel does not significantly affect the aerogel structure in the range of scales from 1 nm to ~1.5 µm, as probed by small-angle X-ray and neutron scattering.

Catalysts for the partial oxidation and dry reforming of methane based on hydroxo salts [AlMg2NixCoy(OH)6.08][(NO3) ⋅ nH2O], where x, y = 0, 0.005, 0.01, 0.02, 0.03, 0.035, and 0.04, with a hydrotalcite-like structure and a total Ni and/or Co content of no more than 2 wt % have been synthesized. It has been shown that Ni–Co catalysts with x = 0.03–0.035 and y = 0.005–0.01 provide a synthesis gas yield of 97–99% in both processes. At a low cobalt loading, the catalysts hardly form carbon nanotubes or other carbon depos-its.

The structure of SiO2-based materials obtained by hydrolysis of tetraethoxysilane and subsequent drying of SiO2 lyogels at temperatures from 85 to 265°C has been analyzed in detail. It has been found that drying conditions have no marked effect on the specific surface area of SiO2, which constitutes ~1000 m2/g in all cases. Average pore size and specific pore volume monotonically increase with drying temperature, the contribution of large mesopores (>20 nm) into total material porosity rises at high drying temperature. Drying temperature has a considerable effect on the degree and character of individual SiO2 particles aggregation.

Hybrid bromobismuthates of N-alkylated derivatives of 2- and 3-methylpyridine, (C15H20N2)2Bi2Br10 (I), (C17H24N2)2Bi2Br10 (II), (C18H26N2)3(Bi2Br9)2 (III), (C14H18N2)(H3O)BiBr6 ∙ 2H2O (IV), (C14H18N2)2BiBr6IBr2 (V), (C16H22N2)3(Bi2Br9)2 (VI), and (C18H26N2)3(Bi2Br9)2 (VII), are synthesized in concentrated HBr and characterized by physicochemical methods. The structures of complexes I–VII are studied by X-ray structure analysis (CIF files CCDC nos. 1946844–1946850). Complexes I and II contain anions [Bi2Br10]4–. Anions [Bi2Br9]3– are found in the structures of compounds III, VI, and VII. Bis(3-methyl-1-pyridino)ethane bromobismuthate IV contains cations H3O+ and anions [BiBr6]3– and, unlike other bromobismuthates, decomposes at low temperatures. In presence of HI vapors, double bromobismuthate V containing the [BiBr6]3– and IBr2– anions crystallizes along with compound IV.

Reversible photochromic hybrid organic–inorganic films containing nanocrystalline cellulose as a matrix and tungsten oxide as a photochromic component (CNC/WO3) were obtained via a simple and quick solvent casting method. The films were studied by scanning electron microscopy, together with element mapping, FT-IR spectroscopy and X-ray diffraction, confirming successful incorporation of WO3 nanoparticles into a nanocellulose matrix. Thermal analysis data indicated that the modification of a nanocellulose matrix with WO3 increases its thermal stability. The CNC/WO3 films showed a quick coloration-bleaching transition with good reversibility within 20 min, without notable degradation of photochromic properties after 10 cycles. The synthetic method proposed allows for scalable preparation of highly efficient low-cost WO3-based photochromic materials.

A procedure for the chemical immobilization of a new ZnII–EuIII heterobimetallic complex in the SiO2 aerogel matrix has been developed. In this Zn–Eu complex, a peripheral non-luminescent Zn ion acts as a binder to a silica matrix and prevents direct interaction of rare-earth ions with OH− and NH− groups in the silica matrix, which would have a detrimental effect on the luminescence of lanthanides. The procedure includes the synthesis of complexes, co-gelation of the obtained complex with SiO2 sol, the washing of lyogels, and their subsequent supercritical drying in CO2. The composition and properties of the obtained aerogels were investigated using a low-temperature nitrogen adsorption technique, helium pycnometry, FTIR, Raman, UV–visible, and luminescence spectroscopy, XPS, PXRD, SEM, TEM, TGA combined with mass spectrometry, and small-angle neutron scattering. The aerogels modified with the ZnII–EuIII complex demonstrated strong red luminescence upon excitation with UV light.

A facile procedure was developed for the production of Al2O3 aerogels modified with tris(8-hydroxyquinolinato)aluminum complex (AlQ3). The addition of 8-hydroxyquinoline during the stage of alumina lyogel formation was found to increase gelation duration. The translucent monolithic aerogels were obtained by supercritical drying of lyogels in CO2. The composition and properties of aerogels were analyzed using low-temperature nitrogen adsorption, helium pycnometry, IR spectroscopy, UV–visible spectroscopy, luminescence spectroscopy, powder X-ray diffraction, scanning and transmission electron microscopy, and thermogravimetry combined with mass spectrometry. The obtained aerogels had low density (0.15–0.18 g cm−3), high specific surface area (480–550 m2/g), high porosity (90–95%), and showed bright luminescence upon excitation in the UV range.

SiO2-based aerogels have been produced be removing a solvent (ethanol or hexafluoroisopropanol) from lyogels both above and below the critical temperature of the alcohols (in the range 210–260 and 160–220°C, respectively). The resultant materials have been characterized by low-temperature nitrogen adsorption measurements, X-ray diffraction, thermal analysis, scanning electron microscopy, X-ray microanalysis, and small-angle and ultrasmall-angle neutron scattering. The results demonstrate that removing the solvent 20–30°C below the critical temperature of the solvent yields silica that is characterized by higher specific porosity and has the same or a larger specific surface area in comparison with the aerogels produced by drying under supercritical conditions. The nature of the solvent used and the solvent removal temperature influence the size and aggregation behavior of primary clusters and the cluster aggregate size in the aerogels.

A comparative analysis of properties of SiO2–TiO2 binary aerogels prepared by supercritical drying using different supercritical fluids (isopropanol, hexafluoroisopropanol, methyl tert-butyl ether, and CO2) has been performed. The use of different supercritical fluids allows preparation of both homogeneous amorphous SiO2–TiO2 binary aerogels (by supercritical drying in hexafluoroisopropanol and CO2) and composite aerogels containing nanocrystalline anatase (by supercritical drying in isopropanol and methyl tert-butyl ether). The thermal treatment of the aerogels at temperatures up to 600°C does not lead to considerable change in the porous structure and phase composition of the aerogels.

A new method of synthesis of nanosized metal oxide powders (Al2O3, MgO, ZnO) has been suggested. The method involves successive heat treatment at 350°С and then at 800°С of saturated solutions of the corresponding metal salts and sucrose. Physicochemical and technological properties of the synthesized materials have been determined.

SiO2‒TiO2 binary aerogels obtained by the methods of low-temperature (carbon dioxide) and high-temperature (isopropanol, hexafluoroisopropanol and methyl tert-butyl ether) supercritical drying are considered as multifunctional cosmetic pigments with high anti-shine power and photoprotective properties. The composition and structure of SiO2–TiO2 aerogels obtained by supercritical drying in various fluids were studied by IR spectroscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, scanning and transmission electron microscopy, and low-temperature nitrogen adsorption. The values of the sun protection factors SPF and UVAPF for the obtained materials are comparable to those of the commercial sunscreens Kronos 1171 and Kronos 2971, and the anti-shine power is approximately 1.5 times higher than that of kaolin-based materials.

SiO2–TiO2 binary aerogels have been synthesized for the first time using methyl tert-butyl ether as supercritical fluid. It has been shown that the aerogels prepared in methyl tert-butyl ether and isopropanol contain nanocrystalline anatase and that amorphous SiO2–TiO2 aerogels with a homogeneous distribution of their components can be obtained in CO2. A considerable contribution to the large specific surface area of the aerogels is made by micropores, especially when supercritical drying is carried out in CO2 and isopropanol.

The title of the article should read as follows: Structural Analysis of Aluminum Oxyhydroxide Aerogel: Small Angle Scattering Studies

Hybrid aerogels (AGs) containing NH2-group were acylated by benzoic and salicylic acids. The acylated AGs had the specific area value of 170-220m2/g and were not deacylated in H2O-iPrOH mixture at 37°С during 24h. In 0.5% HCl at 37°С hydrolysis takes place releasing free acids and giving the possibility to use aminoaerogels as drug delivery system.

Correction for ‘Inkjet printing of silver rainbow colloids for SERS chips with polychromatic sensitivity’ by K. E. Yorov et al., RSC Adv., 2016, 6, 15535–15540.