СТРУКТУРНЫЕ ОСОБЕННОСТИ ПРИРОДНЫХ И ОБОГАЩЕННЫХ КАОЛИНОВ МЕСТОРОЖДЕНИЙ РЕСПУБЛИКИ БЕЛАРУСЬ

IR-spectroscopic results of study of primary kaolins of the Belarusian deposits «Sitnica» and «Dedovka» in a natural state and enriched by hydraulic sieve method are presented. The structural features of Belarusian kaolins as compared with known high-quality kaolin of Ukrainian deposits «Prosyanovskoe» are revealed, the values of crystallinity index are determined. Analysis of IR-spectra in the high-frequency region allowed us to establish the water connection forms in natural and enriched kaolins, the presence of OH-groups in the interlayer space, inside and on the surface of the octahedral layer and adsorbed water molecules, which can affect the rheology of kaolin suspensions. Silicate absorption band of kaolin, as well as intense peaks of deformation vibrations of quartz, typical for unenriched natural kaolin of Belarusian deposits, are in the lowfrequency region. Investigation using IR-spectroscopy made it possible to establish the structural features of natural kaolins related to the presence in the primary kaolin of the «Sitnitsa» and «Dedovka» deposits of the mineral of the kaolinite group of dikkite. The crystallinity index values (according to Hinckley) are established for natural and enriched kaolins «Sitnica» (0.94 and 1.11) and «Dedovka» (0.98 and 1.04) in comparison with kaolins of Prosyanovskoye deposit (1.31). Представлены результаты ИК-спектроскопического исследования первичных каолинов белорусских месторождений «Ситница» и «Дедовка» в природном состоянии и обогащенном гидравлическим ситовым способом. Выявлены структурные особенности каолинов Республики Беларусь по сравнению с известным высококачественным каолином украинского месторождения «Просяновское», определены значения индекса кристалличности. Анализ ИК-спектров в высокочастотной области позволил установить формы связи воды в природном и обогащенном каолинах, наличие ОН-групп в межслоевом пространстве, внутри и на поверхности октаэдрического слоя, а также адсорбированных молекул воды, что может оказать влияние на реологические свойства каолиновых суспензий. В низкочастотной области сосредоточены полосы поглощения силикатных структур каолинов, а также интенсивные пики деформацинных колебаний кварца, характерные для природных необогащенных каолинов белорусских месторождений. Исследование с помощью ИК-спектроскопии позволило установить структурные особенности природных каолинов, связанные с присутствием в первичных каолинах месторождений «Ситница» и «Дедовка» минерала каолинитовой группы диккита. Определены значения показателя индекса кристалличности (по Хинкли) для природных и обогащенных каолинов «Ситница» (0,94 и 1,11) и «Дедовка» (0,98 и 1,04) в сравнении с известным просяновским каолином (1,31).

Hybrid nanoparticles based on sulfides, oxides, and carbides

The methods for synthesis of hybrid nanoparticles based on sulfides, oxides, and carbides of heavy and transition metals were considered. The problem of the influence of the method of synthesis of the hybrid nanoparticles on their atomic structure, morphology of the nanomaterials, and functional properties was analyzed. The areas of practical use of the hybrid nanoparticles were proposed. © 2013 Springer Science+Business Media New York

Origin of Axial and Radial Expansions in Carbon Nanotubes Revealed by Ultrafast Diffraction and Spectroscopy

The coupling between electronic and nuclear degrees of freedom in low-dimensional, nanoscale systems plays a fundamental role in shaping many of their properties. Here, we report the disentanglement of axial and radial expansions of carbon nanotubes, and the direct role of electronic and vibrational excitations in determining such expansions. With subpicosecond and subpicometer resolutions, structural dynamics were explored by monitoring changes of the electron diffraction following an ultrafast optical excitation, whereas the transient behavior of the charge distribution was probed by time-resolved, electron-energy-loss spectroscopy. Our experimental results, and supporting density functional theory calculations, indicate that a population of the excited carriers in the antibonding orbitals of the nanotube walls drives a transient axial deformation in ∼1 ps; this deformation relaxes on a much longer time scale, 17 ps, by nonradiative decay. The electron-driven expansion is distinct from the phonon-driven dynamics observed along the radial direction, using the characteristic Bragg reflections; it occurs in 5 ps. These findings reveal the nonequilibrium distortion of the unit cell at early times and the role of the electron(phonon)-induced stress in the lattice dynamics of one-dimensional nanostructures

Refractory clay raw materials of republic of belarus for production of the porcelain tile

The possibility of replacing imported refractory clays and kaolines, which are part ofporcelain stoneware mix, with refractory clay materials of the Republic of Belarus, in particular quartz- pyrophyllite-kaolinite rock and kaolin of “Dedovka” and “Sitnitsa” deposits, was explored. Porce- lainised stoneware body formulations of JSC “Keramin” (Minsk, Republic of Belarus) was taken as the basis. It was found that physico-chemical properties and operational characteristics ofporcelain tiles comply with the requirements of EN 14411: 2014, when adding 2.5-15.0 wt.% quartzpyrophyllite-kaolinite rock. Incorporation o f quartz-pyrophyllite-kaolinite rock in percentage higher than 15.0 wt.% resulted in reduction in the total amount o f the vitreous phase ofporcelain stoneware, thus increasing water absorption, apparent porosity as well as reduces flexural strength and bulk density. The main crystalline phases in the synthesized materials were quartz and mullite. It was also revealed that imported kaolines could be completely replaced by kaolines o f “Dedovka” and “Sitnitsa” deposits. In this, required physico-chemical properties and operational characteristics of porcelain tiles was maintained. SEM analysis revealed that specimens synthesized using considered kaolines show quite dense microstructures, with a high degree o f vitrification. The gas phase in these materials was practically absent, the presence o f only individual small irregular pores was found. XRD analysis indicated that the major phases were mullite, quartz, microcline and hematite. It was hematite that gives the obtainedporcelain stoneware samples a dark gray color scheme. Thus, the use of domestic refractory clay raw materials provides import substitution and declining production costs

Low-expanding ceramics based on ferrous cordierite

Целью данной работы является проведение исследований в области синтеза керамических материалов технического назначения на основе системы FeO-Al[2]O[3]-SiO[2], которая позволит выровнять недостатки традиционной кордиеритовой керамики