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The paper proposes an explanation of the physicochemical processes occurring during the electric-arc plasma-chemical synthesis of carbon nanomaterials. A diagram of the action of forces on charged particles and a diagram of forces acting on the motion of ions in an arc in the presence of a magnetic field for the plasma-chemical synthesis of carbon nanomaterials are presented and considered. The levels of organization of matter in an arc discharge during the formation of carbon vapour with an increase in temperature are considered. A comparative characterization and a conditional scheme for the formation of various carbon nanostructures during plasma-chemical synthesis are proposed. The sequence of carbon transformations during the formation of carbon nanomaterials and the conditional levels of organization of matter with the types of processes occurring on each of them during structure formation, as the classification of carbon structures by size levels under conditions of temperature decrease from plasma temperature to room one are established. Carbon nanomaterials are synthesized by the plasma-chemical method, and the analysis of the obtained and processed carbon nanostructures is carried out by the following methods: scanning electron microscopy, transmission electron microscopy, Raman spectral analysis, UV–VIS spectroscopy, spectrophotometric analysis. The presence of fullerenes in the products of plasma-chemical synthesis is established, and fullerenes are extracted from the synthesized wall soot. [ABSTRACT FROM AUTHOR]

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The preparation of ceramic composites based on metal nanopowders allows us to change significantly the thermal characteristics of the ceramic matrix, which is important for the creation of heat-conducting ceramics technology. The work establishes the most efficient method of obtaining nickel nanopowder on a “P-5848” potentiostat by electrolysis of nickel sulfate (NiSO4) with the addition of boric acid (H3BO3), thiourea ((NH4)2CS) and nickel(II) chloride (NiCl2). The synthesis of Ni nanopowder was carried out at a current density from 1.0 to 3.3 A/dm2 and at a temperature of 45–65 °C, where a platinum (Pt) plate was chosen as an anode, and the cathode was specially made of especially pure aluminum (Al). The results of the study showed the synthesis of Ni nanopowder with a size of 55 nm in the form of thin scales. Electrochemical reactions at the cathode and anode are also considered in the work. Several successful experiments were also carried out in the work, which made it possible to develop an economically profitable technology for the synthesis of copper nanopowder by the electrolysis method at 13.3 ampere-hours of current per 1 dm2 of the anode surface at a relatively low temperature of the copper sulfate solution (CuSO4). Copper nanopowder is removed to the bottom of the bath from the anode by impact shaking. An equally successful experiment was carried out, where the cathode was in the form of several copper plates at the distance of 0.8 cm from each other with a voltage between them of 0.775 V, and a current density of 15.3 A/dm2 at the temperature of 54 °С in an electrolyte with 45 % H2SO4, 8 % Na2SO4 and 4 % CuSO4. The work contains tables with initial and final data of all experiments on the synthesis of nanopowders by the electrolysis method. [ABSTRACT FROM AUTHOR]

We review and analyse the factors affecting the solubility of interstitial atoms (H) in the metal alloys. The electronic structure and atomic ordering of the AB-type alloys, as well as methods of calculation of the solubility for ordering cubic alloys with octahedral interstitial pores are considered. We study the parameters of interstitial atoms, which make it possible to predict a decrease or increase in solubility, when the main role belongs to the ordering of the system. The parameters of the static distribution of atoms are determined. The relative solubility is represented as a function of the long-range order parameter (η), and the influence of bulk effects on this parameter is considered. The following systems are studied: Fe--Ni, Au--Cu, Pd--Au, Fe--Cr, Ti--Al, Cu--Zn, Ag--Zn, Fe--Al, Au--Ag, Fe--V, Pd--Pt, Ni--Mn, Ni-- Fe, Cu--Au, Cu--Pd, Pd--Nb, Pd--Ag, as well as three-component alloys. As shown, through introducing impurities into the alloy, we can change significantly its physical- mechanical, electrical, magnetic, and other properties. [ABSTRACT FROM AUTHOR]

This paper describes an experiment that made it possible to obtain helical multiwalled carbon nanotubes (НMWCNTs) with a diameter of 30-60 nm by pyrolysis of hydrocarbons and trapping the product with a liquid seal. For the purpose of comparative analysis, the paper also considers the synthesis of straight multiwalled carbon nanotubes (SMWCNTs). Such carbon nanotubes after preparation can be used in CJP 3D printing technology. All obtained materials are examined using the method of transmission electron microscopy. The paper considers the processes of synthesis of HMWCNTs and SMWCNTs. An assessment of the strength characteristics of 3D products from various composites based on them after discrete 3D printing and sintering is carried out. The conditions for the synthesis of carbon nanostructures by the pyrolytic method are described, methods for preparing synthesis products for their subsequent using in 3D printers of CJP, FDM, SLA, SLS technologies are developed, and the technology for preparing mechanical mixtures for 3D printers of CJP technology is developed. In addition, a technique for creating 3D products from composite materials is considered. The bending strength of 3D printed ceramics reinforced with carbon nanotubes is measured. The dependence of the bending strength of the obtained ceramics on the amount of MWCNTs in the composite is established. The resistance to mechanical destruction of composites (MWCNTs-Al2O3) obtained using helical and straight MWCNTs is studied. At the same time, it is shown that when using SMWNT, after the integrity of the composite is broken, the parts of the product do not crumble, but remain united even under load. [ABSTRACT FROM AUTHOR]

The mechanical mixtures of titanium oxide (TiO2) with carbon nanostructures for 3D printing of CJP technology, which are used as consumables for the manufacturing of electrically conductive composite 3D products, are created in this work. Various carbon nanostructures (single- and multi-walled carbon nanotubes and carbon nanofibers) were used in the creation of composite 3D products (TiO2-CNS) by CJP 3D printing technology. Optimal conditions for processing of mechanical mixtures (TiO2/MWCNT) on a planetary ball mixer for composite 3D products (CJP) were studied and proposed. The dose of the deformation influence on the mechanical mixture under optimal conditions of mechanochemical processing (76 J/g), which allows not to deteriorate the electrical conductivity of the material, is determined. The dependence of the electrical conductivity of composite 3D products (CNS/TiO2, where the CNS content is 3 wt. %) on the type of carbon nanostructures (SWCNT, MWCNT and CNF) contained in ceramics (TiO2), is constructed. The exponential dependence of the specific electrical conductivity (G) of composite 3D products (TiO2-MWCNT) on the mass content of multi-walled carbon nanotubes, is also recorded in the work. In the framework of the study of the electrical conductivity of composite 3D products (CJP), a fuel cell cathode based on a Pt/TiO2-MWCNT composite was created. It was found that the catalyst Pt/TiO2-MWCNT, which contains 5 wt. % of carbon nanotubes, has the best catalytic activity in oxygen recovery. At the same time, the average particle size of platinum (Pt) is 5-10 nm, while the content of Pt in the EDX samples is approximately ~10 wt. %. Also, studies were carried out from the mixing of Pt/TiO2-MWCNT composites with MWCNT content 15 and 50 wt. %. Samples were analyzed by transmission and scanning electron microscopy. [ABSTRACT FROM AUTHOR]

Carbon nanostructures (CNS) were synthesized by the electric arc plasma chemical method during the evaporation of a high-quality graphite electrode of the brand “fine-grained dense graphite” (FGDG-7) filled with a catalyst (Pt), which was evaporated in a helium environment. In the synthesis process, the following were synthesized: multi-walled (MWCNT) and single-walled carbon nanotubes (SWCNT), fullerenes, graphene packets and nanocomposites. A deposit in the form of growth on the cathode electrode was also synthesized. All synthesis products were analyzed at the micro- and nanolevels, which made it possible to analyze the influence of platinum vapors on the formation of carbon nanomaterials (CNM). The non-uniform distribution of catalyst atoms (platinum) in the products of electrochemical synthesis in a gas medium using FGDG-7 graphite was investigated. During the analysis, it was found that platinum is in the state of the face-centered cubic (FCC) lattice and is distributed in the synthesis products as follows: the core of the deposit is less than < 0.001 %, the shell of the deposit is less than < 1 %, the wall soot is more than > 1 %. The morphology and composition of the platinum deposit, which has a hexagonal graphite structure with an admixture of a rhombohedral graphite phase, was studied. In the studies, differential thermal analysis in air (TG, DTG, DTA) was carried out, which made it possible to identify the composition of the synthesis products. It is an established fact that the parts of the deposit with platinum are more heat-resistant compared to the deposit components that do not contain Pt. The resulting carbon nanotubes (CNTs) in diameter (5–25 nm) and length (1.5–2 μm) do not differ from those obtained without the participation of platinum, except for some anomalies. When studying the suitability of platinum-containing carbon nanostructures for 3D printing of CJP (ceramic printing) technology, it was found that for the use of platinum-containing carbon black, it is necessary to carry out a preliminary short-term treatment, namely, grinding in special “ball mills” or rubbing through a fine sieve with minimal effort to create uniformity product. Previous studies have shown that such platinum-containing carbon nanostructures can already be used in 3D printing of CJP technology, or to create new composites for 3D printing technologies of FDM, SLA. [ABSTRACT FROM AUTHOR]

We study the experimental and theoretical works concerned with the description of state-of-the-art methods for the preparation of iron-containing endohedral metallof)ullerenes (EMF), as well as works, which dispute such results due to the extremely low efficiency of the used methods. We discuss the features of traditional methods for the fabrication of endometallofullerenes, their advantages and disadvantages, and indicate the areas of possible application of the synthesis products. As shown, the EMF is obtained mainly by two methods, namely, arc discharge (plasma) and synthesis using ablation and implantation methods. Despite a very small number of works on iron endometallofullerenes, the group of authors achieved some progress in their analysis. Thus, the fact of obtaining the Fe-containing endometallofullerenes with their isolation from a mixture of synthesis products is proved. In addition, the influence of the magnetic state of metal atoms on the stability of endohedral fullerenes is predicted, a relationship between the EMF output and the plasma temperature as well as the chemical nature of the precursor of Fe atoms are established. Particularly, as found, with an increase of the group number in the periodic table, in which the metal is located, the EMF yield decreases exponentially. We conclude that, due to the magnetic properties of EMF, they are prospective materials in the field of clinical diagnostics (e.g., as a contrast agents in the magnetic resonance imaging) and medicine (for magnetically controlled delivery of drugs directly to a diseased organ). [ABSTRACT FROM AUTHOR]

Fullerenes-A new combining atoms of carbon atoms into the molecule, which can serve as the parent and precursor of a whole class advanced organic compounds. Unsolved problems associated with a correct understanding of the structure, transformation, and behavior of the fullerene C 60 molecule, make it impossible to interpret correctly many of its physicochemical properties. Fullerenes are a new compounds of carbon atoms into a molecule that can serve as the parent and precursor of the whole class of the newest organic compounds. Unresolved problems connected with correct understanding of structure, transformation and behavior of fullerene molecule C 60 , do not allow to interpret many of its physico-chemical properties correctly. Since the discovery of fullerenes and the subsequent study of their properties, the interaction of fullerenes with metals is of fundamental interest. C 60 -building block (molecule), is similar to the atom, which can be used to create new materials. It has its physical and chemical properties, which a separate atom can't exhibit. First of all it concerns the fact that this molecule, unlike all molecules known up to the present time, has its own surface. The presence of the surface allows the fullerene molecule to behave as a molecule and as a solid nanoparticle. The dualism of the fullerene molecule allows it, unlike other carbon allotropic forms, to dissolve in various liquid mediums. The presence of the surface allows fullerene to enclose in its volume separate atoms and molecules. After the initial detection of fullerenes, multiple attempts are made to obtain, distinguish and characterize fullerenes containing metal atoms in their volume. In the present work the research of the products formed in joint arc evaporation of graphite and gadolinium is carried out. The products formed on the cathode and on the reactor walls are investigated. On the example of gadolinium-containing endofullerenes the conditions of formation of nanoproducts in plasma conditions, in solutions and at their crystallization are discussed.

In the present manuscript the authors show the progress recorded regarding the main synthesis methods of metal endo-fullerenes. Shown, that nowadays, the most productive and common method of producing endohedral fullerenes is the electric arc process due to the fact that (a) it is simple enough to introduce atoms into the plasma from solids and gases; (b) its performance is the highest among other methods; (c) gives a wide range of produced types of metallofullerenes in an inert atmosphere-mono-, di-, tri-metalfullerenes, metal carbide clusters, in a reactive atmosphere (N₂, NH₃)-metal nitride and cyanide clusters, heterofullerenes; (d) provides the greatest energy potential, which is likely to allow the introduction into the cells of fullerene molecules metal atoms with higher ionization energies than titanium (≥7 eV). The yield of metal endofullerenes is substantially higher than the "empty" fullerenes. In this case, the stabilization of both metal atoms and fullerene cells occurs. The quantitative and qualitative output of MEF is significantly affected by: (a) conditions of the process in the reactor: the gas pressure, its flow rate, temperature, amperage; the distance between the electrodes, and others, that is, those factors that determine the plasma temperature and the residence time of the reaction particles in it; (b) the composition of solid additives (salts, oxides, metal alloys) in the graphite anode and their quantitative (mol) ratio with carbon; (c) replacement of the inert atmosphere of the synthesis with the active one (helium-with nitrogen, ammonia, water vapor, CO and other gases).