Octadecahedral and dodecahedral iron nanoparticles: An atomistic simulation on stability and shape evolutions

• Thermodynamic behaviors of octadecahedral and dodecahedral iron nanoparticles were investigated.
• The octadecahedral nanoparticles possess better structural stability at smaller sizes.
• The dodecahedral nanoparticle exhibits better thermal stability.
• The octadecahedral nanoparticle presents better shape stability.

Fe nanoparticles have attracted great interest due to their potent magnetic and catalytic properties which strongly depend on the structures and morphologies. In this article, molecular dynamic simulations were employed to investigate structural and thermal stabilities of body-centered cubic Fe nanoparticles with octadecahedral, dodecahedral and spherical shapes. Size-dependent structural stability was firstly examined. Subsequently, computer simulations on the heating process of octadecahedral Fe nanoparticle discovered that {100} facets premelt earlier than {110} ones. As a result, the dodecahedral nanoparticle enclosed by {110} facets exhibited a better thermal stability than the octadecahedral one terminated by both {110} and {100} facets. Nevertheless, it was found that the octadecahedron presented a better shape stability than the dodecahedron by monitoring the shape factor and statistical radius during continuous heating. This study provides a significant insight not only into the experimental preparation of polyhedral Fe nanoparticles but also into their utilization in high-temperature environments.