Papers by Dmitry Danilovich
Ceramics
Phase transformations in the lithium aluminosilicate glass nucleated by a mixture of yttrium and ... more Phase transformations in the lithium aluminosilicate glass nucleated by a mixture of yttrium and niobium oxides and doped with cobalt ions were studied for the development of multifunctional transparent glass-ceramics. Initial glass and glass-ceramics obtained by isothermal heat-treatments at 700–900 °C contain YNbO4 nanocrystals with the distorted tetragonal structure. In samples heated at 1000 °C and above, the monoclinic features are observed. High-temperature X-ray diffraction technique clarifies the mechanism of the monoclinic yttrium orthoniobate formation, which occurs not upon high-temperature heat-treatments above 900 °C but at cooling the glass-ceramics after such heat-treatments, when YNbO4 nanocrystals with tetragonal structure undergo the second-order transformation at ~550 °C. Lithium aluminosilicate solid solutions (ss) with β-quartz structure are the main crystalline phase of glass-ceramics prepared in the temperature range of 800–1000 °C. These structural transforma...
Heritage, Feb 11, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Izvestiya vuzov. Poroshkovaya metallurgiya i funktsional’nye pokrytiya
The LaB6–VB2 alloy with the eutectic structure was obtained by cold crucible induction melting fo... more The LaB6–VB2 alloy with the eutectic structure was obtained by cold crucible induction melting followed by crystallization. The mole ratio of components in the initial powder mixture was 35 : 65. The structure and composition of the LaB6–VB2 material were studied by X-ray diffraction, scanning electron microscopy, and X-ray microanalysis. The composition of the alloy is represented by two boride phases — cubic LaB6 and hexagonal VB2. Two-phase eutectic regions up to 500 μm in size represent a LaB6 matrix filled with 0.8–2.0 μm thick VB2 fibers (filamentary, rod crystals). VB2 fibers are predominantly oriented along the direction of the temperature gradient that appeared when cooling the melt, i.e. from the outer surface of the sample to its center. The integrated phase area analysis was used to determine the eutectic composition: 42 Ѓ} 1 mol% LaB6 and 58 Ѓ} 1 mol% VB2.
Journal of Composites Science
The ZnO-SnO2-Fe2O3 composites containing flower-like particles were prepared by the non-isotherma... more The ZnO-SnO2-Fe2O3 composites containing flower-like particles were prepared by the non-isothermal polymer-salt method. Thermochemical processes proceeding during composites synthesis was studied by DTA/TG method. The structure and morphology of obtained composites were studied by the SEM and XRD analysis. Prepared composites containing small amounts of SnO2 and Fe2O3 demonstrate the high adsorption and photodecomposition of the organic dye Rhodamine 6G in its solutions. Obtained materials show the ability of the photogeneration of the chemically active singlet oxygen under the visible irradiation. The synergistic effect of the flower structure and Fe2O3 doping can significantly improve the photocatalytic and adsorption activities.
Eutectic structures in quasi-ternary ultrahigh-temperature systems based on ZrB2 and LaB6
Sustainability, 2021
Samples of Chernobyl fuel debris, including massive corium and “lava” were collected inside the C... more Samples of Chernobyl fuel debris, including massive corium and “lava” were collected inside the Chernobyl “Sarcophagus” or “Shelter” in 1990, transported to Leningrad (St. Petersburg) and stored under laboratory conditions for many years. In 2011 aged samples were visually re-examined and it was confirmed that most of them remained intact, although some evidence of self-destruction and chemical alteration were clearly observed. Selected samples of corium and “lava” were affected by static leaching at temperatures of 25, 90 and 150 °C in distilled water. A normalized Pu mass loss (NLPu) from corium samples after 140 days was noted to be 0.5 g/m2 at 25 °C and 1.1 g/m2 at 90 °C. For “lava” samples NLPu was 2.2–2.3 g/m2 at 90 °C for 140 days. The formation of secondary uranyl phases on the surface of corium and “lava” samples altered at 150 °C was confirmed. The results obtained are considered as an important basis for the simulation of fuel debris aging at Fukushima Daiichi nuclear pow...
Nanosystems: Physics, Chemistry, Mathematics, 2020
The effect of hydrothermal-microwave treatment time at 180 • C on the phase composition, dimensio... more The effect of hydrothermal-microwave treatment time at 180 • C on the phase composition, dimensional parameters of crystallites and nanoparticles of solid solutions of lanthanum and yttrium orthophosphates in the system 0.53LaPO 4-0.47YPO 4-(nH 2 O) has been determined. It has been proposed the mechanism for structural transition of lanthanum-yttrium orthophosphate solid solution with rhabdophane structure into monazite structure, which consists in the degeneration of nanocrystals having rhabdophane structure along certain edges into monazite structure. It is shown that phase nanoparticles of monazite structure having average crystallite size of 15-17 nm begin to form after 30 minutes of hydrothermalmicrowave treatment at 180 • C immediately after complete crystallization of amorphous phase in the system. The nanoparticle size increase (length of nanorods) with monazite structure after the stage of their formation occurs, mainly due to matter transfer from nanoparticles having rhabdophane structure to nanoparticles having monazite structure. In this case, the system considered conditions of hydrothermal treatment (temperature-180 • C, pressure ∼1-1.5 MPa, duration-up to 120 min) remains two-phase.
E3S Web of Conferences, 2020
The paper presents the results of studies of the technologically significant properties of munici... more The paper presents the results of studies of the technologically significant properties of municipal solid waste (MSW) compost produced by MSW processing enterprises in St. Petersburg (Russia) where the Dano drum process is implemented. The chemical and microbiological composition of compost, as well as heat during ripening, are investigated. The chemical composition of industrial compost produced in St. Petersburg does not make it possible to use it as fertilizers and soil in agriculture. From the microbiological point of view, NSW compost is not dangerous, but the content of indicator groups of microorganisms classifies it as contaminated soil. The heat generation of compost during ripening is uneven - the largest share of heat 78.5% is released in the first year of maturation. In absolute terms, this value is 3250 kJ/kg by dry weight. To ensure the process is carried out during a period when the compost temperature is higher than the ambient temperature, toxic substances must be ...
Izvestiâ vysših učebnyh zavedenij. Priborostroenie, 2018
Study of Microbiological Aspects of Waste Processing at Experimental Mechanized Waste Processing Plant
Bulletin of the Saint Petersburg State Institute of Technology (Technical University), 2017
European Journal of Inorganic Chemistry, 2019
This paper reports on the grafting of rare‐earth metal ions onto particles of 4–5 nm carboxylated... more This paper reports on the grafting of rare‐earth metal ions onto particles of 4–5 nm carboxylated detonation nanodiamond (DND‐COOH). Aqueous solutions of acetates and nitrates (Ln(OOCCH3)3·4H2O or Ln(NO3)3·6H2O, Ln = Eu, Gd) were used for the grafting. The ion exchange reaction between rare metal ions and protons of surface carboxyl groups was first detected by conductometry and electrokinetic potential measurements. The equivalence point corresponds to the bond between Ln3+ and the three carboxylate anions of DND‐COOH. Thus, we have demonstrated an easy synthetic approach for obtaining nanodiamond particles DND‐COOH with surface grafted with a controlled amount of any rare‐earth metal ions (DND‐COO‐ {Ln}, Ln = Ce, Pr, Sm, Eu, Gd, Dy, Ho, Tm). The resulting hybrid material DND‐COO‐{Eu} exhibits photoluminescence properties arising from f‐f transitions of Eu3+ ion.
Applied Clay Science, 2019
Present study focuses on crystal violet adsorption by mineral halloysite and synthetic pecoraite ... more Present study focuses on crystal violet adsorption by mineral halloysite and synthetic pecoraite nanoscrolls. Being scrolled in opposite directions, these two materials serve both as good adsorbents and model objects to understand the dye adsorption mechanism. Heat treatment of the nanoscrolls allowed us to track the adsorption process features by changing the structure and surface state of the particles. Structural transitions were observed by complementary techniques including X-ray diffraction, thermal analysis, electron microscopy, N 2 adsorption and ς-potential measurements. By a fast UV/VIS study of adsorption kinetics, it became possible to take a closer look at the very initial steps of the process. Intraparticle diffusion governs the overall adsorption kinetics of the dye by halloysite and pecoraite nanoscrolls. The presence of OH-groups on the nanoscrolls' surface strongly facilitates the initial stage of adsorption. Structural transition at around 600°C increases adsorption rate and performance of synthetic pecoraite due to ς-potential sign change. + Cl − , which induces carcinogenic, and possible mutagenic, activity (Docampo and Moreno, 1990; Thompson et al., 1999). Hydrosilicates constitute a broad class of abundant and commercially available materials, which are very attractive as adsorbents (
Izvestiya Vuzov. Poroshkovaya Metallurgiya i Funktsional’nye Pokrytiya (Universitiesʹ Proceedings. Powder Metallurgy аnd Functional Coatings), 2016
Санкт-Петербургский государственный технологический институт (технический университет) (СПбГТИ (Т... more Санкт-Петербургский государственный технологический институт (технический университет) (СПбГТИ (ТУ)) Статья поступила в редакцию 09.03.16 г., доработана 14.03.16 г., подписана в печать 16.03.16 г. В приближении модели регулярных растворов проведено моделирование поверхности ликвидус в квазитройных эвтектических системах SiC-B 4 C-Me d B 2 (где Me d B 2-CrB 2 , VB 2 , NbB 2 , TaB 2 , TiB 2 , ZrB 2 , HfB 2 , W 2 B 5) на основании экспериментальных данных о граничных системах и индивидуальных соединениях. Выполнено сравнение расчетных данных с экспериментальными. Проанализированы закономерности строения диаграмм состояния систем SiC-B 4 C-Me d B 2. Отмечено закономерное снижение концентрации диборида в тройной эвтектике с ростом его температуры плавления. Построены корреляционные зависимости между температурой эвтектики и температурой плавления: t эвт = f(t пл Me d B 2), энтальпией образования диборида: t эвт = f(ΔH f Me d B 2). Характер зависимостей близок к наблюдавшимся ранее аналогичным зависимостям в граничных квазибинарных системах SiC-Me d B 2 и B 4 C-Me d B 2. На основании анализа строения и параметров анализируемых систем сделан вывод о перспективности разработки на основе рассмотренных систем широкого спектра конструкционных и функциональных керамических материалов и покрытий, получаемых «свободным» спеканием, а также импульсными методами нагрева и консолидации. Ключевые слова: карбид бора, карбид кремния, диборид титана, диборид хрома, эвтектика, фазовые равновесия, ликвидус, тугоплавкие соединения, сверхтвердые материалы. Орданьян С.С.-докт. техн. наук, профессор кафедры химической технологии тугоплавких неметаллических и силикатных материалов СПбГТИ (ТУ) (190013, г. Санкт-Петербург, Московский пр., 26).
MRS Proceedings, 2015
ABSTRACTThe aim of this research was to work out the technology of ceramics for finding optimal s... more ABSTRACTThe aim of this research was to work out the technology of ceramics for finding optimal sintering temperatures and to study their mechanical properties. Samples were prepared from powders with different volumetric ratio of the components. The powders underwent a prolonged co-milling in a vibratory mill, followed by uniaxial pressing, cold isostatic pressing (CIP) and pressureless sintering in a vacuum furnace under an argon atmosphere. Hot pressing (HP) was applied to some powder formulations. This study showed that it is advisable to carry out the first stage of the heat treatment up to 1550 ̊C under vacuum, with the aim of refining the grain surface from the oxygen-containing impurities due to their dissociation and evaporation. The studied area of formulations has a very narrow range of sintering (1940-1945 ̊C). It was established that the sinterability of the materials is affected by the amount of silicon carbide in the ternary system. Under pressureless sintering, the r...
Nonoxide High-Melting Point Compounds as Materials for Extreme Conditions
AST, 2014
Authors have studied the interaction between high-melting compounds from various classes, such as... more Authors have studied the interaction between high-melting compounds from various classes, such as transition-metal carbides, borides, nitrides, and silicides, and covalent-bonded B4C, SiC, Si3N4, AlN etc. (over 160 phase diagrams), ternary B4C-SiC-MedB2, SiC-TiC-TiB2 and other eutectics, which is important for optimizing the sintering temperature, material design and prediction of properties of many materials for high temperature applications including wear, aggressive, impact and radiation conditions. A vast identified group of eutectics with number of components n ≥ 2 has reduced eutectic temperature Тeut. (in some sistems reducing reaches 1200 °C). Noted, that increasing of n suppresses grain growth, which is particularly important for developing nanostructured ceramics via pressureless sintering and for controlling the ceramic's performance. Multiphase ceramics (SiC-TiC-TiB2, B4C-SiC-MedB2, B4C-W2B5-MedB2, B4C-LnB6-MedB2, etc.) feature improved mechanical parameters and high wear and impact resistance.
Russian Journal of Applied Chemistry, 2010
Possibility of synthesizing a number of tricalcium phosphate samples by the sol-gel method was an... more Possibility of synthesizing a number of tricalcium phosphate samples by the sol-gel method was analyzed. The effect of the dispersity of tricalcium phosphate on the physicomechanical characteristics of a ceramic sintered from this material.
Nanosystems: Physics, Chemistry, Mathematics, 2017
Effect of ammonium dihydrogen phosphate admixture on phase transitions in nanostructured solid so... more Effect of ammonium dihydrogen phosphate admixture on phase transitions in nanostructured solid solutions (1 − x)KH 2 PO 4-(x)(NH 4)H 2 PO 4 at x = 0, 0.05 and 0.15 has been studied by dielectric spectroscopy. The samples have been prepared by embedding of aqueous solutions into porous borosilicate glasses. The X-ray diffraction have shown that the crystal structure at room temperature corresponds to the bulk KDP and the average nanoparticle diameters are 49 (2) nm for the sample with 5 % of (NH 4)H 2 PO 4 (ADP) and 46 (2) nm for the nanocomposites with 15 % of ADP. Dielectric response data analysis have revealed the shifts of the ferroelectric phase transition temperature as a function of (NH 4)H 2 PO 4 concentration: at x = 0 ∆T C is equal to ∼6 K, at x = 0.05 ∆T C ∼3 K and at x = 0.15 ∆T C ∼2 K.
Authors have studied the interaction between high-melting compounds from various classes, such as... more Authors have studied the interaction between high-melting compounds from various classes, such as transition-metal carbides, borides, nitrides, and silicides, and covalent-bonded B4C, SiC, Si3N4, AlN etc. (over 160 phase diagrams), ternary B4C-SiC-MedB2, SiC-TiC-TiB2 and other
eutectics, which is important for optimizing the sintering temperature, material design and prediction of properties of many materials for high temperature applications including wear, aggressive, impact and radiation conditions.A vast identified group of eutectics with number of
components n ≥ 2 has reduced eutectic temperature Тeut. (in some sistems reducing reaches1200 °C). Noted, that increasing of n suppresses grain growth, which is particularly important for
developing nanostructured ceramics via pressureless sintering and for controlling the ceramic's performance. Multiphase ceramics (SiC-TiC-TiB2, B4C-SiC-MedB2, B4C-W2B5-MedB2, B4C-LnB6-MedB2, etc.) feature improved mechanical parameters and high wear and impact resistance.
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Papers by Dmitry Danilovich
eutectics, which is important for optimizing the sintering temperature, material design and prediction of properties of many materials for high temperature applications including wear, aggressive, impact and radiation conditions.A vast identified group of eutectics with number of
components n ≥ 2 has reduced eutectic temperature Тeut. (in some sistems reducing reaches1200 °C). Noted, that increasing of n suppresses grain growth, which is particularly important for
developing nanostructured ceramics via pressureless sintering and for controlling the ceramic's performance. Multiphase ceramics (SiC-TiC-TiB2, B4C-SiC-MedB2, B4C-W2B5-MedB2, B4C-LnB6-MedB2, etc.) feature improved mechanical parameters and high wear and impact resistance.