The Atomic Mechanism of the Melting Process of Free-standing Hexagonal Boron Nitride

The atomic mechanism of the melting process of the free-standing h-BN is studied using Molecular dynamics simulation. The critical value of the Lindemann criterion for the free-standing h-BN is defined at 0.0326 which is used to classify solid-like and liquid-like atoms. The influence of the edge types on the melting process is observed based on the study of the free-standing hexagonal boron nitride (h-BN), armchair h-BN nanoribbon, and zigzag h-BN nanoribbon using molecular dynamics simulation. Due to dangling bonds at the armchair edge, the phase transition from crystalline to liquid in armchair h-BN nanoribbon occurs at a lower temperature (3700 K) than in zigzag h-BN nanoribbon (4200 K), and the free-standing configuration (4550 K). At the melting temperature, most B atoms in the zigzag h-BN nanoribbon exhibit coordination numbers of one or two, whereas most B atoms in the armchair h-BN nanoribbon and the free-standing h-BN have a coordination number of zero.