A molecular dynamics study of sintering between nanoparticles

The paper presents a molecular dynamics study on the interactions between nanoparticles at elevated temperatures. The emphasis is on the comparison between the molecular dynamics model and the continuum model using solid state physics. It is shown that the continuum model is unable to capture the sintering behaviour of nanoparticles. This is not because the continuum theory does not apply at the nano-scale but because the nanoparticles behave in so many different scenarios of the continuum theory that a meaningful model has to predict these scenarios, using the molecular dynamics for example. In the MD simulation, it is observed that the particles reorient their crystalline orientations at the beginning of the sintering and form different types of "necks" between different particles. This leads to different mechanisms of matter redistribution at the different necks. It is also observed that the particles can switch the mechanism of matter transportation half-way through the sintering process. It would be very difficult, if not impossible, to handle these complexities using the continuum model. However assuming the right scenario, the continuum theory does agree with the MD simulation for particles consisting of just a few thousands atoms.