The study of separation of crystal Fe and morphology for FeB nanoparticle: Molecular dynamics simulation

The separation of Fe crystal from amorphous nanoparticle (NP) has been studied using molecular dynamics simulation. The simulation shows that the NP is crystallized through three stages. In the first stage NP undergoes the relaxation which results in forming nucleation regions where the atomic arrangement is similar to the distorted crystalline lattice. During the first stage the nuclei are unstable and dissolve for short times. In the second stage the stable crystal clusters have been created and new nuclei are formed mainly in the boundary region of crystal cluster. The stable crystal cluster grows in the direction to cover the core and then spreads out to the surface of NP. For the third stage the crystal cluster grows slightly with times. Further study concerns the different morphologies of NP. We found that the crystalline NP comprises a Fe crystalline grain with defects and separate clusters of Am-atom. Comparing to the amorphous NP, the structure organization of crystalline NP is more complicated and cannot be described by the simple shell/core model.