Dynamic Observation of Anisotropic Chainlike Structures during Nonclassical Two-Step Nucleation in Solid-State Iron...

Area of Science:

• Materials Science
• Solid-State Chemistry
• Nanotechnology

Background:

• Understanding atomic interactions in solids is key.
• Self-crystallization nucleation from amorphous precursors is poorly understood.
• Nonclassical nucleation pathways are an active research area.

Purpose of the Study:

• To investigate the dynamic crystallization process of iron oxides.
• To elucidate the nucleation pathway of solid-state crystallization.
• To validate theoretical models of nonclassical nucleation.

Main Methods:

• In situ transmission electron microscopy (TEM) for dynamic observation.
• Molecular dynamics (MD) simulations incorporating Lennard-Jones and magnetic dipole-dipole potentials.
• Free energy profile calculations.

Main Results:

• Observed formation of semi-ordered chainlike structures preceding lattice growth.
• Confirmed a two-step nucleation pathway via MD simulations.
• Identified distinct roles of interatomic potentials at different distances.
• Calculated free energy profiles evidenced stabilization of an intermediate state.

Conclusions:

• The study demonstrates a two-step nucleation mechanism for iron oxide crystallization.
• Findings support and advance nonclassical nucleation theory.
• Provides insights into atomic interactions governing solid-state phase transitions.