Heterogeneous crystallization of hard spheres on patterned substrates

Area of Science:

• Materials Science
• Computational Physics
• Chemical Engineering

Background:

• Crystallization of monodisperse hard spheres is crucial in materials science.
• Homogeneous crystallization can involve long-lived metastable fluid states.
• Substrate effects on crystallization are not fully understood.

Purpose of the Study:

• To numerically investigate the crystallization of hard spheres on patterned substrates.
• To explore how patterned substrates influence crystallization kinetics and resulting structures.
• To determine if specific substrate patterns can stabilize non-bulk crystal phases.

Main Methods:

• Numerical simulations of hard sphere crystallization.
• Utilizing various patterned substrates, including square patterns.
• Analyzing the duration of metastable fluid states and observed crystal structures.

Main Results:

• Patterned substrates drastically reduce or eliminate metastable fluid states.
• A square patterned substrate induced a transient body-centered cubic (bcc) crystal phase.
• Crystallization becomes complex with incommensurate substrate patterns.
• Certain patterned substrates can generate face-centered cubic (fcc) or hexagonal close-packed (hcp) phases with stacking faults.

Conclusions:

• Substrates act as effective seeds, accelerating hard sphere crystallization.
• Square patterned substrates show potential for stabilizing bcc crystal structures.
• Substrate commensurability with the bulk crystal significantly impacts crystallization complexity.
• Engineered substrates can control crystal phase formation, bypassing external factors like gravity.