Vapor Condensed and Supercooled Glassy Nanoclusters

Area of Science:

• Materials Science
• Computational Chemistry
• Condensed Matter Physics

Background:

• Understanding the formation and properties of glassy materials is crucial for developing advanced materials.
• Nanocluster formation presents unique challenges and opportunities compared to bulk or thin-film glasses.
• Investigating the role of formation pathways on glassy structure and dynamics is an active research area.

Purpose of the Study:

• To investigate the structural and dynamic properties of glassy nanoclusters formed through different methods.
• To compare the stability and structural characteristics of nanoclusters with other glassy systems, such as thin films.
• To elucidate the relationship between inherent structure energy, formation history, and the potential energy landscape.

Main Methods:

• Molecular simulation techniques were employed to model nanocluster formation and properties.
• Voronoi polyhedra analysis was used to characterize local atomic structure and identify stable motifs.
• Intermediate scattering function measurements at varying radii probed the relaxation dynamics within the nanoclusters.

Main Results:

• Energetic stability of nanoclusters correlates with a high fraction of bicapped square antiprism motifs.
• Structural similarity was observed for nanoclusters with similar inherent structure energies, irrespective of formation method.
• Inhomogeneous dynamics were found, with a glassy core and mobile surface, facilitating sampling of low-energy states.

Conclusions:

• Glassy nanoclusters are structurally more stable than ultrastable glassy thin films.
• Nanocluster systems do not exhibit superheating effects observed in ultrastable glasses.
• Formation history does not dictate the final low-energy structure accessed by the nanoclusters.