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Molecular-dynamic research of heat capacity of aluminium and gold nanoclusters

Keywords:

V.S. Baidyshev - Ph.D. (Phys.-Math.), Khakas State University, Abakan Yu.Ya. Gafner - Dr.Sc. (Phys.-Math.), Professor, Head of Department, Khakas State University, Abakan


At present, the main problem encountered in the implementation of nanotechnology in the industry is associated not with the design and fabrication of new materials, but rather with the study of the influence of thermal effects and force fields (radiation, deformation, etc.) during the service life of nanomaterials. All these factors should affect the physicochemical, physicomechanical, and other properties, thereby influencing the operational resources of na¬nomaterials. In essence, the heat capacity is a parameter that characterizes the ability of a cluster to accumulate and conserve thermal energy with variations in the temperature. At the same time, the behavior of the heat capacity of nanoparticles (nanoclusters) and nanostructured materials, in general, is associated with the important unsolved problem related to the estimation of its absolute value. On this basis, in the course of the computer simulation we determined the heat capacity of a gold and aluminum nanoclusters with a diameter to 6 nm in the temperature range of 150…800 К and compared the obtained results with the experimental data. It has been found that the heat capacity of a metallic nanoparticles exceeds the heat ca¬pacity of the bulk material by 15 %. Based on the results of the theoretical treatment, computer simulation, and analysis of experimental data, it has been concluded that an increase in the heat capacity of the compacted nanomaterial is not determined by the high heat capacity of individual clusters. Apparently, the significant increase in the heat capacity of compact nano¬materials can be explained either by their disordered state or by the high content of different types of impurities, primarily hydrogen. From this point of view, the results of experimental studies, which predict a manifold increase in the heat capacity of nanoclusters and nanostruc¬tured materials, are obviously erroneous.
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