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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]

Copyright of Progress in Physics of Metals / Uspehi Fiziki Metallov is the property of G.V. Kurdyumov Institute for Metal Physics, N.A.S.U and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A simple approach is presented to synthesise the high-purity MAX phase by the pressureless method. This method is featured by the short time in duration. The process is executed with a high heating rate (up to ≅ 10² K/min) that inhibits the formation of the objectionable phases and limits elemental loss due to the short-time process. The samples containing ≅ 96% wt. of the MAX phase Ti3AlC2 are successfully synthesised using the proposed technique. [ABSTRACT FROM AUTHOR]

The review article describes modern fillers of metal and polymer matrices, their properties and applications. We discuss the main parameters of fillers, their advantages and disadvantages, the results of investigations and experiments, which may be useful for scientists and engineers working in the fields of chemistry and materials science and developing new promising materials. Different materials used as the fillers for metal and polymer matrices are reviewed. To create composites of the new generation with improved properties, nanostructured materials such as graphene, fullerenes, nanotubes, nanopowders of metals and their alloys are used. Carbon fil lers can be the strongest graphitizer, which is important for ferrous metallurgy. Nanofillers have the ultradispersed dimensions and high specific-surface values, which allows for changing significantly the physicochemical and functional characteristics of the matrix. As noted in the article, the use of fillers allows controlling the structural composition of the melt and helps to form additional crystallization centres. This, in turn, can affect significantly the properties of the material, such as mechanical strength, heat resistance, etc. [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]

As part of the work, the hexagonal structure of B19 type metals as hydrogen sorbents will be considered. That is, crystal lattices are considered, where atoms of impurities (hydrogen) are introduced into the interstices of the metal. To do this, we present an image of the B19 structure itself. In this work, the solubility of hydrogen in the crystal structure of B19 type metals was studied using the configuration method, and the dependence on the composition of the alloy and temperature was found in the substitution of nodes and interstices. Also, in the work the degrees of longrange order at the nodes are considered and the parameters of the correlation in the substitution are determined. A graphical view of the effect of atomic order on the solubility of impurities is given. The calculated data obtained in the work coincide with the experimental data of other studies, and the obtained calculation formulas make it possible to determine the energy parameters of the alloys, which is a certain scientific value of the work. The proposed system takes into account only atomic interaction and absorption (dissolution) and diffusion of interstitial atoms into the bulk of the crystal structure; therefore, it is possible to predict the introduction of only a hydrogen atom. Thus, the results obtained in the work of the correlation parameters for the distribution of atoms only in octapores or only in tetrapores allow a deeper study of the physical characteristics of alloys of the B19 type and an understanding of the processes of hydrogen sorption by the working bodies of hydrogen storage. [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]

Copyright of Progress in Physics of Metals / Uspehi Fiziki Metallov is the property of G.V. Kurdyumov Institute for Metal Physics, N.A.S.U and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]

Using a mathematical model of competitive crystallization of polymorphic metals a numerical analysis of formation kinetics of the metastable polytype of lanthanum (µ-La), which is fixed in the products of quenching from the liquid state in a mixture with crystallization of the equilibrium f.c.c. β-modification, is carried out. The interval of rapidly quenched foils thicknesses is determined, within which the metastable µ-phase is formed in quantities sufficient for experimental detection. The calculated data agree with the results of X-ray phase analysis at the physically correct value of the free parameter of the model ΔGµβ = 5 J/mol, which has the meaning of the degree of metastability of µ-La. [ABSTRACT FROM AUTHOR]