Surface-induced melting and structural evolution of Fe2O3 nanoparticles: Insight from molecular dynamics simulation

RB Zeng and H Ding and ZJ Shen and QF Liang and HF Liu, CHEMICAL ENGINEERING JOURNAL, 526, 171094 (2025).

DOI: 10.1016/j.cej.2025.171094

Molecular dynamics simulation is to investigate the atomic thermal diffusion and crystal structure evolution during the surface-induced melting of Fe2O3 nanoparticles (NPs). The melting process of Fe2O3 NPs adheres to the liquid-shell melting mechanism, progressing from surface pre-melting to core melting. The size effect contributes to a reduction in the melting point, with smaller particles exhibiting more pronounced surface energy-induced pre-melting. A gradual decrease in atomic migration activity from the surface to the core, where surface atoms are progressively activated and transferred layer by layer. Fe and O atom transiting forms are coordinated states. Additionally, the local structures of Fe and O atoms transform from body-centered cubic (BCC) and hexagonal close-packed (HCP) arrangements to amorphous configurations, respectively. A critical temperature (1300K) is identified at which Fe2O3 NPs transit from a crystalline to an amorphous state. The surface-induced melting and structural evolution mechanism of Fe2O3 nanoparticles is proposed.

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