Study of the effect of ultrafast heating on the structure and shape of the gas phase synthesized Cu nanoparticless

Abstract

Molecular dynamics method using the tight-binding potential to carry out simulation of ultrafast heating of the synthesized particles from the gas phase to a temperature T = 600 K and T = 900 K, at which the particles were kept about 10 ns. As a result of the simulation revealed that the method of ultrafast heating the particles to high temperatures virtually eliminates the possibility of a clusters of defective education, but as a result of the heat treatment, the some of investigated particles can disconnect (burst) into smaller clusters.

Stability and thermal evolution of transition metal and silicon clusters

“…Under certain thermodynamic conditions, a coherent cluster structure is formed (all atoms both in the bulk and on the surface are considered). The results are in good agreement with the data of computer investigations of the condensation of nickel nanoparticles, 15,80 which demonstrated that coalescence plays an important role at early stages of the synthesis, that is, when the temperature in the system is high. In the case of intense cooling with an inert gas, the temperature rapidly decreases, and agglomeration giving multifractal diplo structures (see above) becomes the predominant growth mechanism.…”

“…5, the cluster formation (bottomup along the time scale) 13,74,79,80 in the metastable gas phase started with homogeneous nucleation. 13,62,64 After completion of this process, different mechanisms of the subsequent growth are possible, the most important of these being agglomeration and coalescence.…”

“…13,62,64 After completion of this process, different mechanisms of the subsequent growth are possible, the most important of these being agglomeration and coalescence. 14,71,80 The cluster agglomeration includes the stage of accretion virtually without change in the shape. Upon coalescence, the clusters are fused to one another to give a single particle with a shape differing from the shapes of the primary clusters before the collision.…”

“…According to MD results, 71,72,74,80 melting of nickel, palladium and gold clusters, unlike melting of macroscopic solids, is extended over a considerable temperature range, which is matched by quasi-melting in the solid-like state. On heating, the Ih clusters of the above-listed metals (for example, nickel) comprising <1000 atoms proved to be energetically more stable (Fig.…”

“…9 b). 71,80 Heating of the Ni 1697 cluster (see Fig. 9 c) resulted in a partial replacement of the hybrid structure (fcc+Dh+Ih) by mainly polytetrahedral packings (Ino+Dh+Ih).…”