D.A. Ryzhkova, S. L. Gafner, Yu. Ya. Gafner.
АННОТАЦИЯ
The influence of decahedral «magic» numbers on the formation of the internal structure of Ag nanoparticles was studied. The particle diameter did not exceed 2 nm. Clusters with fcc and an amorphous initial state were studied. The molecular dynamics method with using a modified tight-binding potential TB-SMA was applied. It was concluded that in the case of small silver nanoclusters, even a clear correspondence of the size to the “magic” number of a particular structure (fcc, hcp, Ih, Dh) cannot guarantee its appearance during the thermal evolution process. If such clusters are subjected to the procedure of smooth heating by gradual supply of thermal energy, then the stochastic diffusion processes occurring in this case can have a very strong effect on the structures ultimately obtained. The presence of various possible polytype transitions was noted, most often leading to the formation of Ih- or Dh-modifications. Despite the fact that the complete fixation of the structure with the fifth-order symmetry axis did not occur during the smooth heating of nanoparticles of different initial morphology, it was shown that the use of clusters with destroyed initial structure to a greater extent allows solving the problem of obtaining particles with the required Ih- or Dh-phase. The fcc structure in clusters of such a small size cannot be considered thermally stable, and to stabilize it, it is necessary to use nanoparticles of a larger diameter. Thus, if the type and quality of the structure is of critical importance for various medical or plasmon applications, then it is necessary to take into account the possible processes of rearrangement of the cluster structure that occur under real operating conditions.
KEYWORDS: computer simulation, nanoclusters, silver, phase transitions, structure
DOI: 10.31857/S0235010622050085