Symmetry breaking and morphological instabilities in core-shell metallic nanoparticles

Area of Science:

• Materials Science
• Nanotechnology
• Physical Chemistry

Background:

• Nanoalloys are metallic nanoparticles (1-100 nm) with diverse applications in catalysis, optics, magnetism, and biomedicine.
• Weakly miscible metal nanoalloys often form phase-separated structures like core-shell and Janus arrangements.
• Understanding these structures is crucial for tailoring nanoalloy properties.

Purpose of the Study:

• To review the structural properties of nanoalloys composed of weakly miscible metals.
• To investigate size- and composition-dependent structural transitions, focusing on core-shell and Janus arrangements.
• To analyze the role of strain and symmetry breaking in governing these structural transformations.

Main Methods:

• Analysis of computational results for various nanoalloy systems (e.g., Ag-Cu, Au-Co).
• Comparison of theoretical findings with experimental observations.
• Application of simple analytical models to rationalize observed structures and transitions.

Main Results:

• Identified size- and composition-dependent transitions between different nanoalloy arrangements.
• Demonstrated that symmetry breaking, driven by atomic-level strain, unifies the understanding of these transitions.
• Analyzed the driving forces behind core-shell formation and the placement of core components within shells.

Conclusions:

• Symmetry breaking provides a unifying concept for understanding structural transitions in weakly miscible nanoalloys.
• The interplay of strain, size, and composition dictates the specific core-shell configurations.
• The review covers equilibrium structures and considers high-temperature and kinetic effects.