Effect of silver shell on melting and crystallization of copper nanoparticles: molecular dynamics simulation

The influence of a silver shell on the melting and crystallization processes of copper nanoparticles was studied using molecular dynamics simulation. The study revealed that the presence of a silver shell leads to a significant decrease in the melting and crystallization temperatures of copper nanoparticles. Moreover, the difference in melting and crystallization temperatures for particles in a vacuum and in a shell increases as the particle size decreases. In the presence of a shell, melting begins from the phase boundary, but at a lower temperature compared to a particle in a vacuum. This is due to the fact that the interaction of different atoms and, moreover, mutual diffusion at the interface leads to a stronger, compared to a free surface, smearing of energy wells of the crystal lattice nodes. In the case of crystallization, the influence of the silver shell was caused by a qualitative change in the mechanism of crystalline nucleus formation: crystallization nuclei were predominantly formed not near the phase boundary, as in the case of a free surface, but, as a rule, on the contrary, in the volume of the “core” of the copper particle.