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The proposed work considers: hydrogen sorption properties of systems of magnesium intermetallic compounds with a complex cubic structure C15b, as promising, reliable, reversible hydrogen accumulators. Considered thermal processes. A statistical theory is proposed for the cubic structure C15b of composition MgRT4Hx, where R = Ce, La, Nd, Pr, Y; T = Co, Ni; 0 ≤ x ≤ 6 at phase transitions in the process of hydrogenation, taking into account pressure. The concentration dependences of the maximum values of the order parameter and a priori probabilities are established. Hydrogen solubility isopleths and isotherms are calculated and considered, and a graphical concentration dependence of the hydrogen atom ordering temperature in MgCeCo4-type crystals is created. The order-disorder transition is considered with allowance for temperature, and the process of absorptiondesorption of hydrogen by the C15b structure is also studied. The equation of thermodynamic equilibrium with the calculation of free energy is derived. And also considered the graphical dependence of the value of the order parameter on temperature and pressure. The temperature dependence of hydrogen solubility in the α, β phases for the MgCeCo4 crystal is considered. The configurational heat capacity of a crystal of the MgSnCu4Hx type structure has been studied, taking into account the temperature and the order parameter. A graph of hydrogen absorption-desorption of the MgCeCo4Hx crystal has been constructed. A comparative analysis of the experimental and practical results of the absorption-desorption of hydrogen by the working fluid of the composition MgRT4Hx has been carried out. [ABSTRACT FROM AUTHOR]

The goal of the research work was the pyrolytic synthesis of straight and spiral carbon nanotubes of approximately the same diameter, as well as their comprehensive analysis. To solve the given problem, a new installation for the pyrolytic synthesis of carbon nanostructures (CNS) with a fusion reactor, which for each fusion process can have its own angle relative to the classical horizontal position of the reactor axis. This reactor made it possible to develop a method for obtaining conglomerates of spiral-shaped multi-walled carbon nanotubes with a diameter of 15–60 nm and to synthesize straight multi-walled carbon nanotubes with a diameter of 5 to 60 nm. The research of pyrolytic synthesis of carbon nanostructures in a vertical reactor allows to work out the technology of purposeful synthesis of nanotubes that have a spiral shape with a certain diameter and pitch of the turn. As part of the work, a new mechanism for the formation of spiral multi-walled carbon nanotubes is also considered and proposed, which is important for their further industrial synthesis and their use in related composites. A scheme is proposed of conditions for the synthesis of carbon nanostructures by the pyrolytic method. Thermal analysis was carried out in the work, which recorded the presence of two different structures with low thermal stability (probably amorphous carbon and higher hydrocarbons). When using scanning and transmission electron microscopy, the formation of spiral nanofibers with a diameter of 15–60 nm in the vertical position of the reactor was recorded, and in the horizontal position of the reactor, the formation of straight and slightly curved MWCTs with a diameter of nanofibers from 5 to 60 nm was found. Raman spectroscopy confirms the presence of multi-layered carbon tubular formation, i.e. MWCT, in both synthesis products. [ABSTRACT FROM AUTHOR]

A review of more than 100 contemporary literary works of domestic and foreign researchers on the issues of electric arc synthesis (EAS) of various carbon nanostructures (CNS) has been performed. EAS CNScan be performed in both gaseous and liquid media. EAS in a gaseous medium has a number of advantages, such as high productivity and velocity of the condensation process, as well as ease of control.But this method of synthesis also has disadvantages: it requires a complex vacuum and cooling system, which makes the installation very cumbersome.In addition, this method does not solve the problem of agglomeration of synthesized CNS and has a by-product of synthesis in the form of growth (deposit) on the electrode. EAS in a liquid medium is more compact equipment, as it does not require systems of vacuum (the process takes place at atmospheric pressure) and cooling (liquid medium plays the role of heat dissipation).This method of synthesis uses different types of dielectric liquids – from distilled water (H2O), liquid nitrogen (N2) to hydrocarbon solvents, which can serve as a source of carbon in the synthesis zone.By changing the composition of the liquid phase, it is possible to achieve the synthesis of different types of CNS.Also, this method involves the use of metal electrodes, which, in addition to long service life, can act as catalysts.The metal particles can be encapsulated ANS, forming composites with different magnetic properties.In some studies, it has been shown that mixtures of metal carbides can be formed when metal electrodes are used in the EAS process in a liquid medium.The liquid medium after EASCNS is also of scientific interest. Probably, the liquid medium contains new modifications of soluble organic compounds, which are being researched by researchers around the world.Thus, scientists have found that after EAS in a liquid medium using graphite electrodes, the working solution (C6H6) changed its color.This indicates the formation of soluble organic compounds in it. In the literature review on the basis of literature data the table of modes for industrial synthesis of single-walled CNS is created.Also, a list of modes for the creation of defective CNS as a method of increasing the area of adsorption in nanoparticles. The solution of important problems of the EAS method is recorded: agglomeration of CNS; the problem of forming a deposit; increase productivity. [ABSTRACT FROM AUTHOR]

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