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Co3 O4 -modified CeO2 (Co/Ce 1:4) was prepared by a combination of sol-gel processing and solvothermal treatment. The distribution of Co was controlled by means of the synthesis protocol to yield three different morphologies, namely, Co3 O4 nanoparticles located on the surface of CeO2 particles, coexistent Co3 O4 and CeO2 nanoparticles, or Co oxide structures homogeneously distributed within CeO2 . The effect of the different morphologies on the properties of Co3 O4 -CeO2 was investigated with regard to the crystallite phase(s), particle size, surface area, and catalytic activity for CO oxidation. The material with Co3 O4 nanoparticles finely dispersed on the surface of CeO2 particles had the highest catalytic activity.

This paper reports the first study on using synthetic silica opals to make ceramic pottery with structural colors. The silica opals were adhered to the pottery substrate by heating at 900°C with a glass phase connecting them. The influence of the heating on the color appearance of the silica opals was investigated in depth. In the study, they were successfully adhered to the pottery substrate with no additives by using the silica opals synthesized with a small amount of catalyst reagent. This finding allows us to control iridescent/non-iridescent coloring of the silica. Additionally, we found unique color changes when the product was wetted. The detailed strategies provided in this paper for synthesizing of silica opals, coating, and heating on pottery are expected to offer useful references for the applications in the field of ceramic art.

Семенов Владимир Викторович – доктор химических наук, ведущий научный сотрудник, Институт металлоорганической химии им. Г.А. Разуваева Российской академии наук, 603950, Бокс 445, ул. Тропинина, 49. E-mail: vvsemenov@iomc.ras.ru. V.V. Semenov, vvsemenov@iomc.ras.ru G.A. Razuvaev Institute of Organometallic Chemistry of the RAS, Nizhny Novgorod, Russian Federation В работе суммированы сведения об узком классе поликонденсированных систем, известных как органо-неорганические гибридные материалы, в которых частицы металлокомплексов внедрены в кремнийоксидную матрицу. Представлены частицы только одного типа – координационные соединения кобальта, хрома, неодима, эрбия и иттербия. Эти материалы получают золь-гель процессом из молекулярных предшественников, которые подвергаются неорганической полимеризации, называемой гидролитической поликонденсацией. Представлены основные сведения о золь-гель процессах. Рассмотрены типы и свойства наиболее распространенных золь-гель мономеров и олигомеров, способы получения металлосодержащих гелей, сделано общее представление о золь-гель процессах, перечислены сферы применения получаемых материалов. Синтезы силоксановых, карбонатных и карбонатно-силоксановых кобальткарбонильные гелей основаны на реакции гомомолекулярного диспропорционирования октакарбонила дикобальта под действием 3-аминопропилтриэтоксисилана, пиридина и диметилформамида. Ряд кремнийорганических аминных гелей получен из 3-аминопропилтриэтоксисилана, хлоридов кобальта(II), хрома(III) и триэтоксисилана. Из кремнийорганических аминных комплексов получены золь-гель пленки, содержащие кобальт, хром и неодим, измерены и интерпретированы их электронные спектры поглощения, показаны превращения, происходящие при абсорбции кислорода и хлористого водорода, измерены нелинейно-оптические свойства. Кремнийорганические амидофосфаты синтезированы взаимодействием 3-аминопропилтриэтоксисилана с бис(диметиламидо)хлорфосфатом и дифенилхлорфосфатом. На их основе получены комплексы эрбия и иттербия, измерены их спектры поглощения и испускания. Приведены два примера иммобилизации металлокомплексов на поверхности высокопористого гидридпо-лисилоксана и лепидоидного силоксена. The paper summarizes information on a narrow class of polycondensed systems known as organic-inorganic hybrid materials, in which particles of metal complexes are embedded in a silicon oxide matrix. There are only one type of particles: coordination compounds of cobalt, chromium, neodymium, erbium, and ytterbium. These materials are prepared by a sol-gel process from molecular precursors that undergo inorganic polymerization called hydrolytic polycondensation. Basic information about the sol-gel processes is presented. The types and properties of the most common sol-gel monomers and oligomers, as well as the methods of obtaining metal-containing gels, are considered, a general idea of the sol-gel processes is described, and the fields of application of the obtained materials are listed. Syntheses of siloxane, carbonate, and carbonate-siloxane cobaltcarbonyl gels are based on the reaction of homomolecular disproportionation of dicobalt octacarbonyl under the action of 3-aminopropyltriethoxysilane, pyridine, and dimethylformamide. A number of organosilicon amine gels have been obtained from 3-aminopropyltriethoxysilane, cobalt(II), chromium(III) chlorides, and triethoxysilane. The sol-gel films containing cobalt, chromium, and neodymium have been obtained from organosilicon amine complexes, their electronic absorption spectra have been measured and interpreted, their transformations during the absorption of oxygen and hydrogen chloride have been shown, and nonlinear optical properties have been measured. Organosilicon amidophosphates are synthesized by the interaction of 3-aminopropyltriethoxysilane with bis(dimethylamido)chlorophosphate and diphenylchlorophosphate. On their basis, complexes of erbium and ytterbium have been obtained, and their absorption and emission spectra have been recorded. Two examples of immobilization of metal complexes on the surface of highly porous polysiloxane hydride and lepidoid siloxene are given. Исследования выполнены в рамках госзадания (Тема № 45.8 Химия функциональных материалов, рег. № 0094-2016-0012) с использованием оборудования центра коллективного пользования «Аналитический центр ИМХ РАН» в Институте металлоорганической химии им. Г.А. Разуваева Российской академии наук при поддержке федеральной целевой программы «Исследования и разработки по приоритетным направлениям развития научно-технологического комплекса России на 2014–2020 годы» (уникальный идентификатор проекта RFMEFI62120X0040). Работа поддержана Российской академией наук, Программа № 35 Президиума РАН «Научные основы создания новых функциональных материалов».

This paper reports on novel cobalt oxide nanoparticles (NPs) embedded in an amorphous silica (SiO2) matrix, synthesized using a modified sol-gel method. SEM and TEM images show as-synthesized particles to aggregate in the shape of spheres and less than 5 nm in size, while XRD and SAED analysis both point to well crystallized cubic spinel cobalt oxide phase with an average crystallite size of about 4.6 nm. Raman analysis confirms the formation of cobalt (III) oxide (Co3O4) NPs. As-synthesized Co3O4 single-nanocrystallite has magnetic properties that correlate with finite size effects and uncompensated surface spins. Temperature dependence of ZFC-FC magnetization curves reveals a sharp peak around 10 K which corresponds to the blocking temperature. A Curie-Weiss behavior of magnetization above 25 K shows lower Neel temperature of the sample compared with its bulk counterpart T-N=40 K (possibly due to crystal defects and nano-dimensionality of the particles). The magnetic measurements exhibit high magnetization at low temperatures (M-s=54.3 emu/g) which can be associated with random canting of the particles surface spins and uncompensated spins in the core which tends to interact ferromagnetically at low temperatures. The initial magnetization curve falls out from the hysteresis loop at 5 K, which could be also the effect of surface spins. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

In this paper, we present the colossal dielectric behavior of T-type La2CuO4-delta (LCO) ceramics synthesized in fine grained form using wet chemical "Pechini" process, followed by annealing in argon (Ar) atmosphere. The colossal dielectric constant (CDC) (10(3)

Yttrium manganite (YMnO3) is widely investigated multiferroic material with potential use in many technological applications. In this paper, we report on the preparation and characterization of multiferroic hexagonal YMnO3 ceramics obtained by chemical synthesis route. Precursor powders were prepared by the polymerizable complex method from citrate precursors. After calcination at 900?C the powders contained mixture of Y-Mn-O phases which were further sintered at different temperatures. XRD analysis revealed that sintering at 1400?C resulted in the formation of pure hexagonal YMnO3. Density of the obtained ceramics was 96%TD. The ceramic samples proved to have multiferroic properties - they are antiferromagnetic below 42K with linear dependence of magnetization as a function of applied magnetic field. The ferroelectric measurements performed at room temperature showed remanent polarization of 0.21 ?C/cm2 and the coercive field of 6.0 kV/cm for the YMnO3 sample sintered at 1400?C. The magnetization curves measured at 2 and 5 K for the powder samples calcined at 900?C and ceramic samples sintered at 1300?C exhibited a hysteresis loop due to a small concentration of Mn3O4 in the samples.

Cordierite ceramic material, due to its properties such as low thermal expansion coefficient, low dielectric constant and high specific resistivity, could be used as an insulating material in high-frequency electronics. as well as a substrate for integrated circuits and electronic modules. In this paper, cordierite (2MgO center dot 2A1(2)O(3)center dot 5SiO(2)) was synthesized by the non-hydrolytic sol-gel process combined with solvothermal treatment starting from aluminium chloride, TEOS and magnesium chloride dissolved in absolute ethanol. Crystallization of mu-cordierite from gel occurred at temperatures between 900 and 1000 degrees C and a higher calcination temperature resulted in the transformation of mu-cordierite to alpha-cordierite. Cordierite material obtained by sintering of powder in the temperature range from 1400 to 1450 degrees C showed values of the dielectric constants from 7.93 to 3.78 and values of dielectric loss tangents from 0.049 to 0.001.

Mullite (3Al2O3·2SiO2) samples doped with 0.4 M, 0.6 M, 0.8 M, 1.0 M and 1.2 M of iron, nickel and Copper, were prepared by a sol-gel process. Prepared gels were then dried, grinded, pressed into pellets and sintered at temperatures 1100°C and 1400°C for 4 h. Phase formation, densification behavior has been investigated as a function of the metal content and sintering temperature. The density of the sintered ceramics was measured using Archimedes method. The main intention is to study the role of metal ions in influencing mullitization behavior in the case of the sol-gel reaction process, in order to provide useful information of mullite. This paper deals with the effect of metal ions on mullite formation, microstructure and densification behavior in single-phase sol-gel derived mullite. The results showed with increase in concentration of metals (Fe2+, Ni2+, Cu2+), crystallization of mullite was enhanced which is evident from X-ray diffraction upto G3 and FESEM of the composites. The density of the doped samples increases with the increase of metal ion concentration as well as with the sintering temperature. Copper-doped mullite exhibits the highest density 2.46 g cm-3 at 1400°C.