The local structure and crystallization of FeB nanoparticle

Using molecular dynamics simulation, we have studied the structural evolution of FeB nanoparticle under annealing and the physical properties of its polymorphs such as crystalline, amorphous and mixed samples. The main focus of present work is the crystallization mechanism and the local structure of polymorphs of FeB nanoparticle. The simulation result shows that the amorphous sample undergoes the crystallization via the nucleation mechanism. During the crystallization, B atoms move out the places where the Fe crystal locates, and diffuse to the boundary region of Fe crystal. The crystal growth proceeds when this boundary region attains specific properties which are defined by the fraction of B atoms and the energies of AB-atoms and CB-atoms. Further our study indicates that unlike amorphous sample, the crystalline and mixed samples consist of three distinct parts including Fe crystalline and two FeB amorphous parts (B-poor and B-rich amorphous part). The different polymorphs of FeB nanoparticle differ in the local structure, size of Fe crystal and energies of different type atoms.