Size-dependent second-order-like phase transitions in Fe nanocluster melting from low-temperature structural...

Area of Science:

• Materials Science
• Computational Chemistry
• Condensed Matter Physics

Background:

• Nanocluster melting behavior is crucial for understanding material properties at the nanoscale.
• The influence of atomic structure on phase transitions in metallic clusters is not fully understood.
• Iron (Fen) nanoclusters offer a model system to investigate these phenomena.

Purpose of the Study:

• To investigate the melting phase transitions of Fen nanoclusters (10 ≤ n ≤ 100 atoms).
• To determine the relationship between cluster structure, size, and melting properties.
• To analyze the occurrence of surface versus core melting and different transition orders.

Main Methods:

• Classical many-body molecular dynamics simulations were employed.
• Melting points (surface, core, and energetic) were calculated for various cluster sizes.
• Heat capacity (Cv) was analyzed to identify transition types.

Main Results:

• Surface melting was observed at significantly lower temperatures than core melting for many Fen nanoclusters.
• Melting properties strongly depend on the nanocluster's specific atomic structure.
• Approximately one-third of the studied cluster sizes exhibited second-order-like phase transitions.
• 1-shell clusters near closed-shell structures showed distinct melting point behaviors.
• Surface melting preceding core melting was observed in larger clusters (>50 atoms) with specific core structures.

Conclusions:

• Nanocluster structure dictates melting behavior, including surface vs. core melting and transition order.
• Closed-shell structures favor first-order-like transitions, while near-closed-shell structures can exhibit unique melting characteristics.
• The findings provide insights into the fundamental phase transition physics of metallic nanoclusters.