The effect of thermal treatment on the organization of copper and nickel nanoclusters synthesized from the gas phase
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The Effect of Thermal Treatment on the Organization of Copper and Nickel Nanoclusters Synthesized from the Gas Phase Yu. Ya. Gafner*, S. L. Gafner, and I. V. Chepkasov Katanov Khakassian State University, Abakan, 655017 Khakassia, Russia *email: [email protected] Received March 25, 2010
Abstract—The condensation of 85000 Cu or Ni atoms from the hightemperature gas phase has been simu lated by molecular dynamics with the tight binding potential. The efect 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. Some tendencies are revealed that are characteristic of the influence of heat treatment on the nanoparticles synthesized from the gas phase. It is concluded that shortterm 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. This opens the fundamental possibility of obtaining Cu and Ni nanoclusters with preset size, shape, and structure and, hence, predictable physical properties. DOI: 10.1134/S1063776110100110
I. INTRODUCTION The need for advanced materials, in particular, for optoelectronic and other devices, stimulates consider able interest in developing methods for the synthesis and processing of nanoparticles. In the general case, these particles can be synthesized from a gas (aerosol processes) or liquid phase (chemical processes). Both variants are widely used for the commercial produc tion of nanostructural powders, for example, of Si, Ti, and C [1, 2]. Nanoclusters obtained using certain methods are already involved in various nanotechnologies. For example, metal nanopowders are widely used as poly functional additives to oils, lubricants, finishing pastes and suspensions. Nanopowders of aluminum, nickel, iron, and some substances are used as activators that accelerate the sintering of some commercial powder mixtures [1]. Metal nanopowders are very promising components for composite materials based on plastics and polymers, which makes possible the production of magnetic plastics, and electroconducting rubber, paints, and glues. A very old but still important and broad field of suc cessful application for fine metal particles is the catal ysis of chemical reactions. Catalysis by small particles plays an extremely important role in commercial chemical processes. Catalyzed reactions usually pro ceed at lower temperatures than similar noncatalyzed processes and are characterized by higher selectivity. For a more extensive list of possible applications of metal nanopowders see, e.g., [1–7] and references therein.
However, the commercial production and use of nanoparticles is seriously limited by the insufficiently developed theory of their n
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