Nanoparticle Superlattices with Nonequilibrium Crystal Shapes.

Area of Science:

• Materials Science
• Nanotechnology
• Crystallography

Background:

• Nanoparticle assembly offers precise control over nanoscale structures.
• Traditional crystal growth analogies aid in predicting unit cell symmetries but not crystallite shapes.
• Kinetics and thermodynamics both influence crystal growth, with kinetics being key for shape control.

Purpose of the Study:

• To demonstrate kinetic control over colloidal crystal shape using nanoparticle building blocks.
• To explore the morphological evolution of these kinetically controlled crystals.
• To expand the diversity of nanoparticle superlattice crystal habits.

Main Methods:

• Utilizing nanoparticle building blocks for rapid assembly across various concentrations.
• Analyzing the influence of assembly kinetics on crystal habit formation.
• Investigating the role of differing mass transport timescales between atomic and colloidal systems.

Main Results:

• Achieved well-defined crystal habits with symmetrically oriented dendritic protrusions.
• Observed that nonequilibrium crystal shapes are more prevalent under near-equilibrium growth conditions.
• Demonstrated that kinetic control is achievable without shaped particles or external agents.

Conclusions:

• Kinetic control offers a powerful strategy to program nanoparticle superlattice morphologies.
• The findings provide generalizable design principles for creating novel crystallite shapes.
• This work enables the synthesis of previously unobserved superlattice structures.