Reshaping, Intermixing, and Coarsening for Metallic Nanocrystals: Nonequilibrium Statistical Mechanical and...

Area of Science:

• Materials Science
• Nanotechnology
• Computational Modeling

Background:

• Supported nanocrystals (NCs) synthesized via vacuum deposition or solution-phase methods form nonequilibrium systems.
• Individual NCs can exhibit far-from-equilibrium shapes and compositions, prone to coarsening (Ostwald or Smoluchowski ripening) which lowers ensemble free energy.
• Preserving NC structure and inhibiting coarsening are critical for applications, particularly in catalysis, to prevent degradation.

Purpose of the Study:

• To review the post-synthesis evolution of metallic NCs.
• To discuss atomistic and coarse-grained modeling approaches for predicting and controlling NC behavior.
• To highlight the importance of realistic kinetic rates and mechanisms in predictive modeling.

Main Methods:

• Atomistic modeling using stochastic lattice-gas models.
• Coarse-grained modeling incorporating realistic mechanisms and kinetics.
• Analysis of reshaping (sintering, pinch-off) and compositional evolution.
• Modeling of coarsening, diffusion, decay, and unconventional processes.
• Integration of modeling with experimental techniques like scanning tunneling microscopy (STM) and in situ transmission electron microscopy (TEM).

Main Results:

• Modeling reveals insights into NC reshaping and compositional changes in vacuum.
• Analyses cover NC coarsening, including diffusion, decay, and unique coarsening phenomena.
• High-level modeling integrated with STM for 2D epitaxial nanoclusters.
• Developments in modeling for 3D NCs informed by in situ TEM studies.

Conclusions:

• Accurate modeling of NC post-synthesis evolution requires realistic kinetic rates for relaxation mechanisms.
• Predictive models are essential for understanding and controlling NC stability and preventing degradation.
• The integration of advanced modeling with experimental techniques like STM and TEM is crucial for validating and advancing the field.