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Polyoxotungssilicates with the general formulas Cat4[SiW12O40] ? mH2O and Cat6[SiW11O39Ni(H2O)] ? nH2O, where Cat = Rb+, Cs+, (CH3)4N+, were synthesized. Using IR spectroscopy and X-ray phase analysis, it was shown that the compounds have the Keggin anion structure. When thermolysis of the resulting compounds in the temperature range 600…800 ?C, previously unknown phases are formed with the pyrochlore structure of the compositions Rb12/13Si2/13W22/13Ni2/13O6 and Cs12/13Si2/13W22/13Ni2/13O6 with unit cell parameters a = 10,284 and 10,309 ? and tungsten bronze Rb12/20Si3/20W36/20O6 and Si3/38W36/38O3. The synthesis of tungstosilicates with a pyrochlore and tungsten bronze structure by thermolysis of polyoxotungssilicates reduces their production temperature to 600…650 ?C and heating time to 1 hour, expands the range of chemical compositions and their morphological diversity.
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A method for obtaining a new composite material based on magmatic gabbro rock reinforced with basalt fiber is proposed. Laboratory samples were obtained and their properties (pycnometric density and Brinell hardness) were determined.
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A method has been developed for one-sided etching of the inlet openings of channels of non-etched blanks of microchannel plates in dilute hydrofluoric acid. Blanks of microchannel plates MCP 18-10 were used in the work. The treatment was carried out in 0.2 n. hydrofluoric acid solution at room temperature without oscillation and mixing of the solution.
The results obtained allow us to assert that the etching of the channel inlets is more than 10 % of the diameter of the MCP 18-10 channels, which increases the electronic transparency of the device.
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The structure of matrix materials synthesized quenching sodium-rubidium aluminoborosilicate melts with the zirconium addition was studied using vibrational spectroscopy. The significant influence of zirconium on the ratio of the main structural units and the distribution of modifier cations was established in the glass structure. The results obtained were used to explain the change in the glass-melt transition temperature and the density of the material, and it is recommended for discussion in the selection of the composition and synthesis parameters of borosilicate matrix materials for the immobilization of high-level radioactive waste containing significant amounts of zirconium.
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It has been shown that the modified sol-gel method (method Pechini) successfully synthesizes multielement oxides based on bismuth niobate, crystallizing in the pyrochlore structure type (space group Fd-3m). The synthesis temperature of a single-phase sample is 950 ?С, which is one hundred degrees lower than the calcination temperature in the traditional ceramic synthesis method. The average crystallite size, determined by X-ray diffraction, varies from 39 (850 ?С) to 48 nm (1050 ?С) depending on the sintering temperature. According to X-ray phase analysis, the unit cell parameter is 10.4872(6) ?. The results of elemental mapping indicate a uniform distribution of metal atoms on the surface of the sample, and X-ray energy dispersive analysis showed that the chemical composition of the synthesized sample corresponded to the specified theoretical composition.
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The possibility of increasing the current density of a beam of charged particles (“focusing”) using tapered glass channels without involving external energy sources is currently being actively implemented for positively charged ions. In relation to electron beams, this possibility is not used due to the lack of experimental data on the process of grazing interaction of electron beams with a dielectric surface. It is necessary to study the degree of compression of the electron beam by tapering capillaries depending on their geometric parameters, as well as to study the time characteristics of the focusing process. In this work, an experimental study of the degree of compression of an electron beam with an energy of 10 keV was carried out using a glass tapering channel 15 mm long with an input/output internal diameter ratio of 1.15 mm/0.3 mm. An increase in the beam current density at the output for a capillary with the above parameters was demonstrated up to 2.7 times for a position where the channel axis is parallel to the axis of the original beam. Moreover, this increase in density is estimated for electrons that have lost no more than 1 keV of their initial energy. The stability of the process of electron transmission by a tapering capillary is also shown, regardless of the orientation of the capillary relative to the direction of the original beam.
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This study is devoted to the study in diagnostics of macro-micro cracks in pipes coated with silicate-enamel, which is a key problem for the structural integrity of piping systems. Silicate-enamel coatings are commonly used to improve corrosion resistance, but the identification of subsurface macro-micro cracks remains challenging. Despite the fact that the process
of diagnosing macro cracks on the surface of the coating is currently underway, the issue of diagnosing macro-micro cracks is still problematic. The article emphasizes the importance of timely detection in order to prevent possible leaks and design failures, emphasizes the consequences for economic development and security. An algorithm for diagnosing microcracks on the surface of pipes with silicate-enamel coating has been developed. The test voltage of the improved electric spark flaw detector was increased to 40 kV, and microcracks of up to 1.5 mm were detected. A method of remote detection of oil leaks from oil trunk pipelines is described. As a result of the diagnostics, the coordinates and geometric parameters
of the cracks are determined.
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Compliance of buildings with fire safety requirements is an important issue for designers and builders. Based on the analysis of statistical data, conclusions are substantiated about the insufficiency of measures to ensure the fire safety of people and the role of glazing in solving this problem. The article examines a topic of mandatory fire safety requirements for glass in building. The analysis of regulatory documentation has been carried out in connection with the recent updating of basic regulatory documents on fire safety requirements. A brief overview of fire-proof glazing and fire-resistant glasses is given. Recommendations are given on the use of fire- proof glazing to increase the safety of people in case of fire.
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Bismuth germanate glasses modified with sodium oxide have been synthesized. The influence of a modifier on the spectral-luminescent properties of bismuth germanate glasses has been studied. The ratios of Bi2O3 and Na2O concentrations
at which IR luminescence of these glasses is possible were found.
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Bismuth-containing chromates BixCrO1.5x+3 with a variable molar ratio of 1 ? n(Bi)/n(Cr) ? 38 were synthesized using
a ceramic method from Bi (III) and Cr (III) oxides. Depending on the n(Bi)/n(Cr) ratio, the calcined samples acquire a color from green to dark red. Ceramics turn red when subjected to high-temperature treatment in air (at 650 ?С) of a mixture
of oxides with a significant predominance of bismuth oxide n(Bi2O3)/n(Cr2O3) ? 3. It is noteworthy that calcination
of chromium (III) oxide under similar conditions does not lead to the oxidation of chromium ions. X-ray phase analysis confirmed the formation of chromates Bi6Cr2O15, Bi10Cr2O21, Bi31Сr5O61.5, Bi14CrO24. Studies of samples using X-ray
spectroscopy showed that the NEXAFS Cr2p spectra of red bismuth-chromium ceramics coincide in the main details
of the spectrum with the K2CrO4 spectrum and indicate the chromium content in the oxide ceramics in the form
of tetrahedral CrO42– ions. According to scanning microscopy data, the samples are characterized by a dense, low-porosity microstructure.
