Competing factors in grain boundary loop shrinkage: Two-dimensional hard sphere colloidal crystals

Area of Science:

• Materials Science
• Condensed Matter Physics
• Statistical Mechanics

Background:

• Grain boundary (GB) loops are boundaries between lattice domains with misoriented orientations.
• Understanding GB loop relaxation is key to controlling grain coarsening.
• Previous studies on 2D colloidal hard sphere solids showed conflicting trends in GB loop shrinkage rates between experiments and simulations.

Purpose of the Study:

• To reconcile contradictory experimental and computational findings on GB loop shrinkage in 2D colloidal hard sphere solids.
• To identify factors influencing the rate of GB loop relaxation.
• To understand the role of preparation methods and grain morphology on shrinkage dynamics.

Main Methods:

• Computational simulations of 2D colloidal hard sphere solids.
• Adjusting lateral packing pressure and domain size in simulations.
• Mimicking experimental protocols for GB loop formation.
• Analyzing GB loop shrinkage rates for hexagonal and starlike grain shapes.

Main Results:

• Computational results were brought into qualitative agreement with experimental findings by modifying simulation parameters.
• GB loop shrinkage rates were found to differ by two orders of magnitude based on grain shape (hexagonal vs. starlike).
• The orientation of dislocations significantly influences the observed shrinkage behavior.

Conclusions:

• The observed trends in GB loop shrinkage are sensitive to simulation parameters and preparation methods.
• Both the energetic barrier for dislocation generation and the dislocation pattern dictate shrinkage dynamics.
• This work provides a pathway to accurately model and predict grain boundary behavior in 2D materials.