Sintering-coalescence transition on the nanoscale as a bifurcation phenomenon: molecular dynamics study

TL;DR

This study uses molecular dynamics simulations to identify a bifurcation point in nanoparticle sintering, revealing a temperature-dependent transition between liquid-like and crystalline coalescence states.

Contribution

It uncovers a critical temperature below the melting point where nanoparticle coalescence behavior bifurcates, a novel insight into nanoscale sintering phenomena.

Findings

Bifurcation temperature T0 is about 0.9 times the melting temperature Tm.

Nanoparticles can have either liquid-like or crystalline structures after coalescence at the same temperature.

The transition is identified as a bifurcation phenomenon in nanoparticle sintering.

Abstract

Using the isothermal molecular dynamics (MD), coalescence/sintering of Au nanoparticles (NPs) was simulated by employing the Nose-Hoover thermostat. The MD simulation was realized by using the well-known open program LAMMPS, its version for parallel calculations on GPUs. We have found that the solid NP sintering scenario is switched to the coalescence scenario not at the NP melting temperature Tm exactly but at a lower temperature T0=0.9Tm interpreted as the critical temperature corresponding to a coalescence/sintering bifurcation phenomenon: in the temperature range from T0-2K to T0+2K the resulting (daughter) NPs of the same size can have either liquid-like or crystalline structure after coalescence/sintering at the same fixed temperature. The crystallize and liquid states were identify by analyzing the degree of crystallinity and the radial distribution function. For this purpose we employed the OVITO program.