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Imeni Vladimira Il’icha Lenina, Russia

Gafner S.L.,Katanov Khakass State University | Gafner J.J.,Katanov Khakass State University | Bardakhanov S.P.,RAS Institute of Theoretical and Applied Mechanics | Lysenko V.I.,RAS Institute of Theoretical and Applied Mechanics
Journal of Computational and Theoretical Nanoscience | Year: 2012

The process of Ni nanoclusters synthesis from the gas phase had been studied by the molecular-dynamics method based on tight-binding potentials. The gas phase was produced after evaporation of melted nickel using high energy electron beam. Experimental procedure originated the nanoparticles of two fractions with average size 100 and 200 nanometers. Computer analysis of system evolution shows the splitting can occur due to consolidation of large enough primary clusters. The simulation shows two stages of system evolution. At the first stage the consolidation occurs for clusters belonging to the range of the largest values of size distribution in accordance with theory predictions. At the second stage the largest probability corresponds to consolidation of biggest particles. Finally it leads to bimodal size distribution which is not observed at usual theoretical analysis of condensation process. © 2012 American Scientific Publishers. All rights reserved. Source


Samsonov V.M.,Tver State University | Gafner Y.Y.,Katanov Khakass State University | Gafner S.L.,Katanov Khakass State University | Zamulin I.S.,Katanov Khakass State University
Eurasian Chemico-Technological Journal | Year: 2012

The heat capacity of nanoclusters was investigated using thermodynamics of surfaces, taking into account the surface enthalpy introduced by E. Guggenhein. It is shown that the cluster heat capacity Cp should be greater than the heat capacity Cp (b) of the corresponding bulk phase. However, the (Cp - Cp (b))/Cp (b) ratio should not exceed 50% up to very small clusters containing 100 atoms. Theoretical estimations agree with molecular dynamics results. So, experimental data on metallic nanoclusters and nanostructures demonstrating that Cp exceeds Cp (b)) in 2-5 times should be incorrect. © 2012 al-Farabi Kazakh National University. Source


Chepkasov I.V.,Katanov Khakass State University | Gafner Y.Y.,Katanov Khakass State University | Gafner S.L.,Katanov Khakass State University | Bardakhanov S.P.,RAS Institute of Theoretical and Applied Mechanics
Bulletin of Materials Science | Year: 2015

Technological applications of metallic clusters impose very strict requirements for particle size, shape, structure and defect density. Such geometrical characteristics of nanoparticles are mainly determined by the process of their growth. This work represents the basic mechanisms of cluster formation from the gas phase that has been studied on the example of copper. The process of Cu nanoclusters synthesis has been studied by the molecular- dynamics method based on tight-binding potentials. It has been shown that depending on the size and temperature of the initial nanoclusters the process of nanoparticle formation can pass through different basic scenarios. The general conditions of different types of particles formation have been defined and clear dependence of the cluster shape from collision temperature of initial conglomerates has been shown. The simulation results demonstrate a very good agreement with the available experimental data. Thus, it has been shown that depending on the specific application of the synthesized particles or in electronics, where particles of a small size with a spherical shape are required, or in catalytic reactions, where the main factor of effectiveness is the maximum surface area with the help of temperature of the system it is possible to get the realization of a certain frequency of this or that scenario of the shape formation of nanocrystalline particles. © Indian Academy of Sciences. Source


Chepkasov I.V.,Katanov Khakass State University | Gafner Y.Y.,Katanov Khakass State University | Gafner S.L.,Katanov Khakass State University
Journal of Aerosol Science | Year: 2016

The gas-phase condensation of 85,000 Cu atoms is examined by molecular dynamics simulation with a tight-binding potential. A detailed study of the evolution of the system cooled at a constant rate from 1000. K to 77. K is presented. The results are used to identify four distinct stages of the evolution from a hot atomic gas to a few synthesized particles. The effect of the subsequent thermal treatment on the shape and structure of synthesized particles was studied by simulating their gradual heating in a range of 100-1200. K. It is concluded that short-term heating leads to significant ordering of the internal structure in 70% of agglomerated nanoparticles with the predominant formation of spherical shapes. In order to explain this result, the main mechanisms of cluster formation from the gas phase have been analyzed and it is found that the agglomeration temperature plays the main role in the formation of clusters with unified shape and structure. © 2015 Elsevier Ltd. Source


Myakhar V.V.,Katanov Khakass State University | Spirin D.V.,Katanov Khakass State University | Udodov V.N.,Katanov Khakass State University
Physics of Metals and Metallography | Year: 2013

A model of the magnetization distribution in thin ferromagnetic films that are in the so-called supercritical state has been considered. The model makes it possible to take into account the real distribution of the magnetization more precisely in ferromagnetic films than open and closed models. The theoretical results have been compared to the experimental data. © 2013 Pleiades Publishing, Ltd. Source

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