New approaches to preparing powder and ceramics of double perovskite Sr2AlNbO6 (SAN) are presented. In addition to the conventional solid-state method, we employed organic solvents, sol-gel synthesis and liquid precursor plasma spraying (LPPS) to deposit SAN ceramic layers. For these purposes, we used a niobium oxalate complex forming stable solutions or gels in DMF with Sr2+ and Al3+ nitrates. We investigated the composition and thermal behavior of solutions, gels and prepared SAN samples and found that DMSO containing Nb precursor yields a stable impurity phase Sr4Al6O12(SO4) inside the final SAN powder. The measured linear thermal expansion coefficient (TEC) of sintered SAN is 12.4 & times; 10-6 K-1 at 1000 degrees C, which exceeds that for yttriastabilized zirconia, YSZ (11 & times; 10-6 K-1). The LPPS SAN coating contains two phases, identified as SAN and an amorphous oxide. The Young's modulus and Vickers nanohardness of SAN in LPPS-coating are also better than those of YSZ coating deposited with conventional atmospheric plasma spraying (APS).

Катализаторы состава NiхCе1-хAlO3-d (x = 0-0.5) готовили методом самораспространяющегося высокотемпературного синтеза в растворе. После термообработки полученных продуктов при 700 °С на воздухе по данным рентгенофазового анализа преимущественно формируется фаза алюмината церия и в небольшом количестве высокодисперсная фаза оксида церия. Увеличение содержания никеля в образце приводит к значительному снижению доли фазы оксида церия. Полученные на основе модифицированного ионами Ni2+ алюмината церия образцы являются предшественниками катализаторов для реакции углекислотной конверсии метана (УКМ) и характеризуется высокой удельной поверхностью и развитой пористой структурой. Изучение фазового состава этих образцов после предварительного восстановления в водородсодержащей газовой смеси («активации») и дальнейшей работы в условиях реакционной среды показало, что ионы Ni2+ восстанавливаются, выходят из структуры на поверхность и формируют частицы металлического Ni размером 5-8 нм. Исследовано влияние химического состава катализаторов на каталитические свойства в реакции УКМ. Представительный катализатор состава Ni0.5Cе0.5AlO3-d показал стабильную работу в реакции УКМ в течение 30 ч при Т=700 °C, конверсии CH4 77%, выходе H2 43% и экстремально малом времени контакта t =30 мс. Высокая каталитическая активность полученных катализаторов в реакции УКМ обусловлена формированием активной фазы в виде высокодисперсных наночастиц металлического Ni, устойчивых к зауглероживанию, на изначально большой удельной поверхности алюмината церия, стабилизированного ионами Ni2+.

Nitric oxide is an important molecule that plays a crucial role in regulating physiological processes in mammals. To develop a sensitive method for detecting NO, new heterostructures based on cobalt phthalocyanine (CoPc) films decorated with Ir-IrO2 nanoparticles were considered as active layers of chemiresistive sensors for the direct NO detection. Within deposition conditions, Ir-IrO2 nanoparticles with an Ir concentration of 0.48-1.5 mu g/cm2, a fraction of IrO2 phase of 10-20 %, and particles sizes from 1 to 3 to 14 nm were obtained on the surface of CoPc films. The influence of these parameters of Ir-IrO2 particles on the sensor response of Ir-IrO2/CoPc heterostructures to NO was investigated using theoretical and practical approaches. Based on DFT calculations, an electronic sensitization mechanism of NO detection by Ir-IrO2/CoPc heterostructures was proposed. These heterostructures are able to detect of NO gas at the ppb level and show the selectively to NOx in the presense of other gases.

Film heterostructures of compositions Ag/Au/Ti and Ag/Au/CFR-PEEK are obtained by thermal evaporation with subsequent deposition of metallic gold sublayers and silver nanostructures on modern biomaterials (Ti-6Al-4V alloy, polyether ether ketone CFR-PEEK). Silver concentration is varied within 2.1-20.8 µg/cm2 by changing the initial metal portion (1.2-5 mg) and the number of successive depositions (1–3). According to SEM data, Ag nanofilms with a thickness up to 10-15 nm are formed on the surface of gold sublayers. According to XPS results, gold is present in the metallic state on the surface of biomaterials whereas along with metal, the Ag2O oxide phase is detected for silver. The dynamics of silver dissolution from the Ag/Au surface is analyzed by ICP-AES (2-48 h). It is found that regardless of the silver concentration, the samples demonstrate moderate dynamics of releasing metal ions; some amount of gold is detected together with silver in the solution. The absence of cytotoxicity of the synthesized film heterostructures in vitro (L-929 cells, viability >95-98

Методом термического испарения получены пленочные гетероструктуры составов Ag/Au/Ti, Ag/Au/CFR-PEEK при последовательном осаждении подслоев металлического золота и наноструктур серебра на современные биоматериалы (сплав Ti-6Al-4V, полиэфирэфиркетон CFR-PEEK). Содержание серебра варьировали в интервале 2.1-20.8 мкг/см2 путем изменения исходной навески металла (1.2-5 мг) и количества последовательных нанесений (1-3). По данным СЭМ, на поверхности золотых подслоев формируются нанопленки Ag толщиной до 10-15 нм. По данным РФЭС на поверхности биоматериалов золото присутствует в металлическом состоянии, тогда как для серебра наряду с металлом регистрируется таже наличие оксидной фазы Ag2О. Методом ИСП-АЭС исследована динамика (2-48 ч) растворения серебра с поверхности Ag/Au. Обнаружено, что, независимо от концентрации серебра, образцы демонстрируют умеренную динамику выделения ионов металла, наряду с серебром в растворе также регистрируется небольшое количество золота. Показано отсутствие цитотоксичности синтезированных пленочных гетероструктур in vitro (клетки L-929, жизнеспособность >95-98%). Гетероструктуры полностью подавляют рост колоний грамотрицательных (P. аeruginosa) и грамположительных (S. аureus) бактерий через 6 и 24 часа воздействия, соответственно.

NixCa1-xAl2O4 samples, where x = 0.1-0.5, were obtained by co-precipitation followed by drying on air at room temperature. After calcination in air at 700 °C, an oxide compound with a defective structure g-Al2O3, in which Ni2+ and Ca2+ ions are stabilized, as well as highly dispersed fragments of NiAl2O4 and NiO was formed. After pretreatment stage (reducing in H2-containing mixture) and work in the reaction medium, nickel is partially reduced to the metallic state and leaves the structure of the compound, forming on the surface highly dispersed Ni0 particles with a size of 3–15 nm. Calcium is stabilized in the structure of g-Al2O3 and on its surface. The introduction by Ca2+ leads to a significant increase in the concentration of not very stable surface and bulk carbonates and bicarbonates, which promotes the oxidation of C-containing intermediate compounds formed on Ni0 centers. In addition, the modification of Ca2+ leads to decrease the concentration of strong acid sites on the surface, the formation of a weaker CO2 bond under reaction conditions, and the fool disappearance of signals from CO complexes with strong LAC, which significantly reduces the amount of carbon, which is formed at the stage of deposition on the surface. The resulting catalysts are characterized by high activity and stable work for a long time in the dry reforming methane reaction.

Методом импульсного химического осаждения их газовой фазы с использованием летучих металлорганических прекурсоров, получены оксидные пленки ZrO2-HfO2. Показано, что способ организации реакционного пространства оказывает влияние на морфологию, толщину и равномерность получаемого покрытия. Установлено, что при дозировании паров прекурсора и газа-реактанта в реактор через разработанную ранее систему раздельной подачи реакционных компонентов, удается получить оксидное покрытие с толщиной 360 нм. По данным атомно-силовой микроскопии, в этом случае формируется практически гладкая поверхность с параметрами среднеарифметической шероховатости в пределах нескольких нм. Для полученных в работе оксидных покрытий состава ZrO2-HfO2, были изучены вольт-амперные (ВАХ) и вольт-фарадные характеристики (ВФХ). Отмечено, что величина пробивного электрического поля практически не зависит от толщины оксидного покрытия (0.1-0.48 МВсм-1) в интервале 225-325 нм. При увеличении толщины оксидной пленки с 325 до 360 нм, наблюдается рост значения пробивного электрического поля. На основании результатов измерения вольт-фарадных характеристик полученных образцов пленочных покрытий состава ZrO2-HfO2, была определена зависимость величины диэлектрической проницаемости от толщины оксидной пленки. Показано, что величина диэлектрической проницаемости линейно зависит от толщины оксидного покрытия.

A synthesis procedure for composite precursors of the composition yttrium-stabilized zirconia nanoparticles – 2,2,6,6-tetramethyl-3,5-heptandionato-hafnium(IV) is developed. The thermal behavior of the synthesized composites is studied by the complex thermal analysis up to 600 °C in a wide concentration range. Main components of thermolysis products are determined by the energy-dispersive X-ray (EDX) analysis. Features are revealed in TG curves for all compositions in the temperature range of 310-410 °C. From the IR, XPS, and EDX data it is found that the observed effects are due to low-temperature decomposition of a small part of the volatile metal-organic precursor irreversibly absorbed on the surface of nanoparticles. A hypothesis is put forward that irreversible adsorption is caused by Lewis acid centers on the surface of nanoparticles. The obtained information about the thermal properties of composite precursorscan facilitate the development of methods to control nanoparticle concentrations in the coating formed.

The ZrO2–HfO2 oxide films are prepared by pulsed chemical vapor deposition using volatile organometallic precursors. It is shown that the morphology, thickness, and uniformity of the resulting coatings are affected by the mode of reaction space organization. A 360 nm thick oxide coating is obtained by introducing the precursor vapor and the reactant gas into the reactor through an earlier elaborated system of separate reaction components supply. The atomic force microscopy data show that the resulting surface is almost smooth and has an arithmetic average roughness of a few nanometers. Current-voltage and capacitance-voltage characteristics of the obtained ZrO2–HfO2 oxide coatings are studied. It is noted that the breakdown electric field is almost independent of the oxide coating thickness (0.1-0.48 MV/cm) in the interval of 225-325 nm. The breakdown electric field increases as the oxide film thickness increases from 325 nm to 360 nm. The dependence of the dielectric constant on the oxide film thickness is determined from the measured capacitance-voltage characteristics of the obtained ZrO2–HfO2 films. It is shown that this dependence depends linearly on the film thickness.

Разработан метод синтеза композитных прекурсоров состава «наночастицы оксида циркония, стабилизированного иттрием - 2,2,6,6- тетраметил-3,5-гептандионато-гафний (IV)». Методом комплексного термического анализа изучено термическое поведение синтезированных композитов до 600 °С в широком концентрационном интервале. Продукты термолиза проанализированы на основные компоненты методом энергодисперсионного анализа. Для всех составов на кривых ТГ выявлены особенности в интервале температур 310-410 °С. На основании данных ИК-спектроскопии, РФЭС и ЭДС установлено, что наблюдаемые эффекты связаны с низкотемпературным разложением небольшой части летучего металлоорганического прекурсора необратимо адсорбировавшегося на поверхности наночастиц. Высказана гипотеза, что необратимая адсорбция связана с кислотными Льюисовскими центрами на поверхности наночастиц. Полученная информация о термических свойствах композитных прекурсоров позволит разработать методы управления концентрацией наночастиц в формируемом покрытии.

NixCo1-xAl2O4 (x = 0–0.5) catalysts were prepared by the co-precipitation from solution of Ni, Co and Al nitrates. The dry gel was heated at 700 °C in air and resulting alumina modified by nickel and cobalt ions is formed with spinel structure. The in situ X-ray diffraction study of these precursors in the reduction by a H2-containing gas mixture at 700 °C and ex situ after preliminary reduction in a H2-containing gas mixture and further work under reaction medium conditions showed that ensembles of Ni-Co alloy particles 3-4 nm in size are formed on the spinel surface. The influence of the composition of the catalysts and the duration of their testing on the catalytic properties in the dry reforming of methane reaction (DRM) was studied. The Ni0.35Co0.65Al2O4 catalyst is stable in the DRM for 20 hours with CH4 conversion of 76 % and an H2 yield of 42 % (T = 700 °C, t = 30 ms). The high catalytic activity of the obtained catalysts in DRM is due to the formation of highly dispersed (3–4 nm) nanoparticles of the Ni-Co alloy an active phase in an amount of 17–18 wt. % on the initially large specific surface area of a spinel, stabilized by nickel and cobalt ions, and possessing mobile bulk oxygen under reducing reaction conditions.

The effect of gadolinium additives on the morphology, phase composition, and catalytic properties of MoVSbNbGdOx/SiO2 catalysts in the oxidative dehydrogenation of ethane to ethylene (ODE) is studied. It is shown that gadolinium concentration has a significant effect on the catalytic properties. At an optimum gadolinium content (Gd/Mo = 0.01–0.015), an increase in catalytic activity and ethylene selectivity is observed: at a temperature of 400°C, the ethylene yield achieves 72

Федеральное государственное бюджетное учреждение наукиИнститут неорганической химии им.А. В. Николаева Сибирского отделения Российской академии наук

The influence of carbon nanotubes (CNTs) on the mechanical properties and structure formation during reactive sintering of B4C materials with Si addition was studied. Upon infiltrating the B4C structure with molten silicon, a non-porous composite was formed with a density of 2.45-2.55 g/cm3 and a hardness of 22-27 GPa. The formation of highly dispersed B-C-Si phases was observed in the interphase of adjacent B4C particles due to the incorporation of Si into B4C structures. These phases increase the bonding strength between B4C particles. In spite of the fact that the addition of 1-5 wt% Multi-Walled Carbon Nanotubes decreases the green density of the compacts, the flexural strength of the infiltrated material significantly increased. The improvement of the strength of ceramics modified with MWCNTs was interpreted in terms of the formation of thin flattened SiC crystals at the interfaces between B4C and B-C-Si particles, which strengthen the interfaces between ceramic particles.

A multicomponent MoVSbNbCeOx/SiO2 oxide catalyst exhibiting high catalytic activity in the oxidative dehydrogenation of ethane to ethylene is synthesized by spray drying of a suspension of aqueous solutions of the precursors and the subsequent heat treatment in He at 350 and 600°C. At a temperature of 400–450°С in a wide ethane conversion range, the catalyst exhibits a fairly high activity and ethylene selectivity. In the presence of this catalyst, the maximum ethylene yield achieves 74% (ethane conversion of 91%, ethylene selectivity of 81.5%); this value significantly exceeds the yield in the presence of Sb-containing catalysts known from the literature. The catalyst exhibits a long-term stable on-stream behavior under reaction medium conditions without any change in the phase composition and a deterioration of the catalytic characteristics. It is shown that the catalytic properties of the synthesized catalyst are comparable to the properties of MoVTeNbOx, which is one of the best catalysts for this process. However, the use of a Te-containing catalyst is limited, because tellurium exhibits a high toxicity and volatility during the synthesis and use of the catalysts. According to X-ray diffraction analysis, the main components of the catalyst are M1 and M2 phases stabilized on a SiO2 surface. The HRTEM data show that a structural feature of the catalyst is the presence of an interface formed by the coherently intergrown crystals of the M1 and M2 phases.

The effect of iron oxide additives on the formation of the microstructure of supported 1 wt % Pt/(Fe2O3–TiO2) catalysts, the electronic state of platinum, and the catalytic properties of the catalysts in the CO oxidation reaction has been studied. The synthesized catalyst has exhibited a higher activity than that of a 1 wt % Pt/TiO2 catalyst at identical amounts of platinum in the samples. It has been found that the introduction of iron oxide in an amount of up to 10 wt % leads to the formation of a solid solution of iron ions in titania with an anatase structure. The supporting of platinum has led to a decrease in the particle size and an increase in the content of platinum in the Ptδ+ state. An optimum chemical composition of the catalyst that provides the highest activity in the studied reaction has been determined.

We develop the method of production of conductive vacuum-tight ceramics based on Al2O3 modified by multiwall carbon nanotubes (MWCNTs) at extremely low their content. The method is based on the use of nanopowders of alpha-Al2O3 combined with application of highly efficient distribution of MWCNTs on the surface of the initial oxide particles, provided by using ultrasonicated MWCNT suspensions stabilized with surfactant. The usage of surfactant destructing of MWCNT agglomerates of structure results in the elimination of cavities in ceramic matrix and improvement vacuum-tight properties of composites. The results can provide the optimization of production technology of strong vacuum-tight ceramics which are perspective for the production of conducting ceramics for accelerating tubes in pulse linear accelerators. Such materials would make it possible to avoid using high-voltage resistive voltage splitters and simultaneously suppress transverse resonance modes usually leading to transverse instability of intense beams in long accelerating structures.

The use of copper oxide complexes (CC) of various structures: CC-I (copper tetrammine complex with the ground state of copper ions (d(x2) - d(y2)), characterized by a weak exchange magnetic interaction in the EPR spectra) and CC-III (Cu2+ ions with the ground state (d(x2) - d(y2)), with the strong exchange magnetic interaction) in the synthesis of Cu/ZSM-5 catalysts allowed us to study the effect of their structure on the physicochemical and catalytic properties in the decomposition of nitrogen (I) oxide (N2O). It was demonstrated by means of H-2-TPR and IR spectroscopy of adsorbed CO that the nature of the reduction of Cu/ZSM-5 catalysts is determined by the state of copper in the catalyst. It was established that the highest catalytic activity is observed for the catalysts prepared using CC-III. Extraframework CuO-like clusters stabilized on the outer surface of zeolite crystallites prepared using CC-III are the most effective centres for the decomposition of nitrous oxide, and the activity of catalysts increases with an increase in copper content.