Alloy, Janus and core–shell nanoparticles: numerical modeling of their nucleation and growth in physical synthesis

Abstract

While alloy, core-shell and Janus binary nanoclusters are found in more and more technological applications, their formation mechanisms are still poorly understood, especially during synthesis methods involving physical approaches. In this work, we employ a very simple model of such complex systems using Lennard-Jones interactions and inert gas quenching. After demonstrating the ability of the model to well reproduce the formation of alloy, core-shell or Janus nanoparticles, we studied their temporal evolution from the gas via droplets to nanocrystalline particles. In particular, we showed that the growth mechanisms exhibit qualitative differences between these three chemical orderings. Then, we determined how the quenching rate can be used to finely tune structural characteristics of the final nanoparticles, including size, shape and crystallinity.

Numerical Modelling of Formation of Highly Ordered Structured Micro- and Nanoparticles – A Review

“…Of course, MD has also been applied for modeling of synthesis of structured NMPs. Förster et al (2019) used a very simple MD model to investigate the dependence of a particle structure on the parameters of the interactions between the atoms. In their investigations, three kinds of atoms have been considered.…”

“…It should be emphasized that even a small particle consists of many hundreds of thousands or even millions of atoms or molecules (e.g. Förster et al, (2019) conducted simulations for 200,000 atoms). Another problem may be to formulate a realistic model of interactions between atoms and molecules that make up the particle.…”

NanoMaterialsCAD: Flexible Software for the Design of Nanostructures

“…[ 1 ] This rapid surge is also attributed to the advances in experimental methodologies regarding the fabrication and application of nanoparticles, thin films, and other nanostructures, simultaneously leading to a demand for more in‐depth theoretical analysis. [ 2–8 ] As a result, one of the main challenges for computational nanoscience is to design increasingly sophisticated simulation models that correspond accurately to real‐life systems and the conditions in experimental setups. [ 9–16 ]…”

Out-of-equilibrium Polymorph Selection in Nanoparticle Freezing

“…However, from the experimental point of view, nanoparticles are usually obtained through out of equilibrium processes especially when using physical routes of synthesis such as laser ablation [29][30][31][32], flame pyrolysis [33][34][35], and magnetron sputtering [29,36,37]. In all these cases, as the temperature is decreased, the system goes from the gas phase to a liquid droplet whose subsequent freezing lead to the formation of a nanocrystal [38][39][40]. While being crucial to reach a rational design of nanoparticles, the highly complex nucleation pathways and the resulting polymorph selection remain difficult to understand in this out of equilibrium context.…”

“…In particular, numerous works investigated the freezing mechanisms in nanoparticles [41][42][43] and how the size and the * julien.lam.pro@gmail.com chemical composition of the liquid droplet can influence the final structure [44]. However, the cooling rate -an important tuning parameter in synthesis experimentshas been scarcely studied [38,40,42,45] even though it provides a primary route to study the interplay between kinetic and thermodynamical pathways.…”