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The paper suggests a design of radiation sensors based on metal-oxide-semiconductor (MOS) structures and p-channel radiation sensitive field effect transistors (RADFET) which are capable to function under conditions of high-field tunnel injection of electrons into the dielectric. We demonstrate that under these conditions, the dose sensitivity of the sensor can be significantly raised, and, besides, the intensity of radiation can be monitored in situ on the basis of determining the ionization current arising in the dielectric film. The paper proposes the model allowing to make a quantitative analysis of charge effects taking place in the radiation MOS sensors under concurrent influence of ionization radiation and high-field tunnel injection of electrons. Use of the model allows to properly interpret results of the radiation control. In order to test the designed sensors experimentally, we have utilized γ-rays, α-particle radiation, and proton beams. We have acquired experimental results verifying the enhancement of function capabilities of the radiation MOS sensors when these have been under high-field injection of electrons into the dielectric.

Space charge-limited currents in Ti–TiO2 thin-film structures have been studied. Using the experimental physical parameters of the TiO2 dielectric, models of the formation of the space charge-limited injection currents have been constructed. The dependences of the injection current on the applied voltage, dielectric layer thickness, and parameters of electron traps have been explored. It is shown that the space charge-limited injection currents in the investigated structures depend significantly on both the depth and concentration of traps. The results obtained are compared with the dependences obtained previously for the BeO, Al2O3, and AlN structures.

A model is proposed for describing a cathode layer of a glow gas discharge in the presence on a cathode of a dielectric oxide film, the thickness of which has different values on different sections of its surface. The influence is studied of the non-uniformity of the film thickness on the effective coefficient of the ion-electron emission as well as on the discharge characteristics.

Pargasite stability was experimentally studied in IHPV at = 2 kbar and temperatures of 1000 to 1100 o C, with equilibrium approached from above and below. Calcic amphibole was used to experimentally model processes that occur in a volcanic chamber at pressures up to 5 kbar. The phase diagram of pargasite has been refined. It has been established that the stability of pargasite is controlled by three reactions. (1) At low water pressures of less than 1 kbar, the dehydration reaction Prg = Fo + Sp + Di + Ne + An + H 2 O proceeds. (2) At water pressures higher than 1.2–1.5 kbar and a temperature of about 1100°C, the decomposition of pargasite is controlled by its incongruent melting Prg = Fo + Sp + { Di + Ne + An } L + H 2 O. (3) The third reaction Prg + L = Fo + Sp + Di + { Ne + Pl } L + H 2 O occurs within the same pressure range as the previous one but at lower temperatures of about ~1050°C. The reaction controls the pargasite liquidus and is caused by interaction between amphibole and coexisting melt. The liquidus of pargasite seems to most strongly depend on the activity of silica in the melt.

The influence of high-field electron injection modes on the charge state and defectiveness of metal–oxide–semiconductor (MOS) structures after irradiation is studied. It is shown that to remove the radiation-induced positive charge accumulated in the SiO 2 film of MOS structures, it is necessary to apply the high-field Fowler–Nordheim tunneling injection of electrons in an electric field that do not cause hole generation. It is established that removing the radiation-induced positive charge in the SiO 2 film of a MOS structure and the generation of new interface traps are mainly determined by the magnitude of the charge injected into the dielectric. It is found that, upon the annihilation of holes trapped in SiO 2 as a result of interaction with injected electrons, a significant increase in the number of interface traps is observed, which significantly exceeds the number of interface traps arising upon the annealing of a radiation-induced positive charge at room temperature. A model is proposed that describes the annihilation of a radiation-induced positive charge upon interaction with injected electrons.

Features of the mechanism of dimethyl ether (DME) conversion to olefins over ZSM-5 zeolite catalysts were studied using experimental and theoretical methods of vibrational spectroscopy. A catalytic activity comparison of the catalysts Mg-HZSM-5 without a binder and Mg-HZSM-5/Al 2 O 3 containing 1% Mg (by weight) and 33% Al 2 O 3 (by weight) as a binder in the DME conversion was carried out. Using high-temperature diffuse reflectance IR (DRIR) spectroscopy in situ combined with quantum-chemical simulations in the temperature range of 25–450 °C in a stream of dry Ar and DME, the bands corresponding to OH bonds, including BAS and H 3 O + , were interpreted. Depending on the temperature and the presence of magnesium and a binder in the catalyst composition, the intensity and position of these bands maxima vary greatly. The intermediates of the catalytic DME conversion were discovered and identified. At low temperatures (below 200 °C), in a DME stream, methoxy groups (CH 3 O-Al-), ketene (CH 2  =C=O), and a carbocation (CH 3  +) were formed on the surface of the catalysts. As the temperature rises (above 300° C), the bands from ketene completely disappear in the spectra of catalysts, and bands from oxonium cations or ylide particles appear, leading the process of DME conversion by the oxonium-ylide mechanism. In the presence of H 3 O + , the conversion of DME on the zeolite catalyst surface was more effective; however, selectivity for olefins was lower. Graphical Abstract

The purpose of this study is to investigate the synthesis process of composite materials based on fir bark for thermochemical transformation and to determine the influence of additives such as zinc chloride, natural graphite of various origins on the structural and electrochemical characteristics of the carbonized products. Modification of fir bark sawdust with amorphous and/or crystalline graphite and zinc chloride allowed for the synthesis of products with a specific surface area of up to 780 m 2 /g and an apparent specific electrical capacity up to 540 F/g. It was revealed that carbonization of samples containing zinc chloride leads to the formation of porous carbon/zinc oxide composites. The solid residue obtained from the mixture of three components (fir bark, crystalline graphite, and zinc chloride) has the highest apparent specific electrical capacity. It is assumed that the combination of the structures of amorphous, crystalline carbon, and zinc oxide promotes the diffusion of electrolyte and the accumulation of electric charge in carbon composite.

The phase formation sequences in 9Sn/91Fe(001) and 25Sn/75Fe(001) bilayers during thin-film solid-state reactions up to 800°C were investigated using X-ray diffraction, the torque method, and scanning electron microscopy. In both samples, FeSn 2 , FeSn, α-Fe 1− x Sn x , Fe 5 Sn 3 , α-Fe, and β-Sn were sequentially formed at the initiation temperatures T in i  ~ 150°C, ~ 300°C, ~ 550°C, ~ 600°C, and ~ 700°C, respectively. Low-temperature transformations were predicted at temperatures T K 1  ~ 150°C and T K 2  ~ 300°C, which are absent in the phase equilibrium diagram of the Fe–Sn system. Solid-state dewetting of the 9Sn/91Fe(001) and 25Sn/75Fe(001) bilayers started at temperatures above 550°C. Overall, this work sheds new light on general chemical mechanisms governing the synthesis of intermetallic phases in Sn/Fe(001) thin films, the phase transformations, and the evolution of the dewetting process of Fe x Sn 1− x films. Graphic abstract

Purpose. Confirmation of the possibility of using a paste fuel based on ammonium perchlorate in a rocket engine and identifying the characteristics of its combustion. Methodology. Previous experimental studies on the burning of paste fuel in a constant pressure bomb determined the burning rate at different pressures. The stability of deflagration combustion without transition to the detonation mode was confirmed. An explosion occurred during the fire test of the engine model on paste-like fuel. The analysis of the causes of the explosion made it possible to put forward a hypothesis about the enrichment of the paste fuel with ammonium perchlorate, which created the prerequisites for its detonation. The conducted additional experiments showed a change in the combustion mode when enriching paste fuel with ammonium perchlorate. Findings. Theoretical and experimental studies have shown the possibility of obtaining detonation fuel based on the enrichment of paste fuel with ammonium perchlorate. It has been proven that, under certain production conditions, paste fuels can detonate, which opens up a new way of using such fuels for rocket engines. The conditions for the transition of the burning mode of pasty fuel from deflagration to detonation combustion are determined. The speed of the engine element during the explosion was evaluated and it was shown that during explosive combustion due to the large area and, accordingly, the mass flow, it is not possible to obtain a pressure value that could ensure the movement parameters registered in this engine design. Originality. Another criterion is established of engine operability when designing an engine on paste fuel. The effect of enrichment of pasty fuel with ammonium perchlorate during its flow through the supply system at the time of start-up was revealed. Practical value. The given information makes it possible to improve the design of the engine on paste fuel and to modernize the stand for its tests.

An effective accelerated synthesis procedure of a carbon material based on chitosan via infrared pyrolysis was developed. Infrared radiation heating allows to shorten preparation time significantly. It takes only 2 min of the residence time at 800 °C for complete carbonization of the polymer. The chemical transformations in chitosan during infrared pyrolysis depended on temperature were studied. The formation of C=C-C=N and C=C-C=C conjugated bonds at a low-temperature stage of the carbonization process was demonstrated. It was revealed that the main product of the chitosan pyrolysis at 600-800 °C represents a graphite-like carbon material in the form of carbocyclic structures.