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The four-component Au-Cu-Pd-Pt nanosystems of different sizes with the stoichiometric composition Au3CuPd12Pt4 were studied. The molecular dynamics method was used as a simulation method, the interatomic interaction was described by the tight-binding potential. Based on the results of a series of computer experiments, it was found that the four-component Au-Cu-Pd-Pt nanoparticles do not have a tendency to form a core-shell structure, even though gold atoms demonstrate an increased segregation to the surface. Melting and crystallization temperatures were determined for the studied Au-Cu-Pd-Pt nanoparticles. The dependence of the crystallization temperature on the cooling rate was also established. With an increase in the cooling rate, the crystallization temperature decreases, and the temperature range in which crystallization occurs increases, while the heating rate does not significantly affect the melting temperature. It is shown that the size effect and the effect of the temperature-changing rate make it possible to control the dominant presence of the fcc or hcp local structure, and also affect the temperature stability of the resulting crystalline phases.

Various types of configurations of the Au-Cu-Pd-Pt four-component nanosystem, including complex core-shell structures, have been studied. The Monte Carlo method was used as a simulation method, the interatomic interaction was described by the tight-binding potential, i.e. the Gupta potential. According to the results of a series of computer experiments, it was found that four-component nanoparticles of this system do not tend to form a core-shell structure, even though gold atoms have an increased surface segregation. The melting temperatures for the nanosystems under study have been determined. The obtained values are in the range from 1100 K to 1250 K and weakly depend on the composition of nanoparticles (the ratio of the number of atoms). A stoichiometric composition based on these metals was found, for which, during cooling, an FCC crystal structure with inclusions of the HCP phase is formed. However, no distinctive features in the nature of segregation for this stoichiometric composition have been established. All considered stoichiometric compositions in the studied temperature range were stable with respect to decomposition.

The melting and crystallization temperatures have been calculated and the phase diagram of Pd — Pt metal particles of 10 nm in size has been constructed. The surface and interfacial energies, their temperature and size dependences were estimated by a modified electron-statistical method. It was found that the form of the phase diagram for Pd — Pt nanoparticles has significant differences from the diagram of bulk phases, including the melting-crystallization hysteresis.

Size dependence of the melting temperature of Si nanoparticles has been investigated combining molecular dynamics and thermodynamic simulations. The results of the atomistic simulation obtained using the Stillinger-Weber potential agree with the results of other authors and with the thermodynamic simulation results based on Thomson’s formula. These results predict that the melting temperature Tm of Si nanoparticles diminishes with increasing their reciprocal radius R-1 following to the linear law. The available experimental data predict much lower values of Tm, including underestimated values of the limiting value Tm(∞) found by means of the linear extrapolation of experimental dots to R-1 → 0 (i.e. to the particle radius R → ∞), and the underestimation of Tm(∞) ranges from 200 to 300 K in comparison with the melting point 1688 K of the bulk crystalline Si. Taking into account the obtained results and their comparison with available results of other authors, a conclusion is made that molecular dynamics results, obtained by using the Stillinger-Weber potential, should be more adequate than the available experimental data on the melting temperature of Si nanoparticles.

The melting and crystallization temperatures of platinum nanoclusters have been found by using results of molecular dynamics modeling, obtained employing two different computer programs and different interatomic interaction potentials. The size dependences found in computer experiments are compared with molecular dynamics data of other authors and with estimations of the melting temperature using Thomson’s formula.

Investigations of thermodynamic and structural characteristics of cobalt nanoclusters in the process of phase transition melting/crystallization with the goal to identify characteristics of their behavior typical for the clusters with the «magic» number of atoms. The melting point of nanoclusters was determined using the temperature dependence of the specific internal energy of nanoclusters.

In this paper, a series of computer experiments on heating of clusters in the form of a truncated box is made by a molecular dynamics method ( NPT ensemble). Clusters of the stoichiometric compositions AB and A3B were investigated for Cu-Ag and Au-Ag bimetallic systems. We used a modified many-body tight-binding potential. It was found that the temperature range of the structural stability for bimetallic nanoparticles (nanoalloys) have combined influence of the following factors: nanoparticle size and initial geometric form, nanoparticle composition, type and degree of atomic ordering, external pressure.

The results are presented on the creation of a composite material for heat sink substrate of semiconductor crystals of power electronics products with a given set of physical and mechanical properties.

In this paper a molecular-dynamics simulation of the structure and thermal stability of the copper clusters size up to 100 atoms has been carried out using many-body tight-binding potential. On the basis of the calculation of a local minimum energy for copper clusters it the «magic» nanoclusters can be found which are more stable. The size dependencies of the thermodynamic and structural characteristics for such clusters demonstrate specific behavior.

The investigation of the thermodynamic characteristics of the gold nanoclusters with «magic» numbers of atoms in melting/crystallization phase transition has been carried out. Using the temperature dependence of the specific internal energy of nanoclusters, the melting temperature has been determined.

Size dependence of the nanocluster melting temperature Tm has been analyzed using some similarity considerations and generalized Thomson’s formula Tm=Tm(∞)(1-α/R) where R is the particle radius, Tm(∞) is the macroscopic melting temperature and α is a parameter having the dimension of length and being the reduction parameter for R. Using Thomson’s formula and extrapolation to Tm=0K, the parameter α was calculated for nanoclusters of several metals with different types of lattice. It has been found that in most cases this parameter is close in magnitude to the first coordination sphere radius.

Size dependences of the melting temperature for supported thin films were calculated using relations obtained earlier. A conclusion is made that the most noticeable size effect should be expected when the film is characterized by the anomalous temperature dependence of the film substance density.