Interfacial Properties of Composites Based on h-BN and c-BN in Function of Temperature: a Molecular Dynamics Study

TL;DR

This study uses molecular dynamics simulations to explore how temperature affects the phase transition between cubic and hexagonal boron nitride in composites, highlighting the role of surface termination.

Contribution

It reveals the influence of surface termination on phase transition behavior and identifies temperature thresholds for h-BN layer formation in composites.

Findings

B-terminated c-BN has lower potential energy than N-terminated c-BN.

At around 700 K, c-BN begins to transition to h-BN.

Higher temperatures lead to formation of free h-BN layers.

Abstract

Using molecular dynamics simulations and the ReaxFF force field, we studied a composite based on cubic (c-BN) and hexagonal (h-BN) boron nitride subjected to different temperatures to verify the possibility of a c-BN to h-BN phase transition. Our results demonstrate that the surface termination of c-BN (whether B- or N-terminated) is a crucial factor in the phase transition. The B-terminated c-BN surface presents a lower potential energy than the N-terminated one. However, compared to the potential energy of h-BN, the B- (N-) terminated c-BN surface has a lower (higher) potential energy than h-BN. As the temperature increases, the potential energy of the B-terminated c-BN surface gradually approaches that of h-BN, leading to the beginning of detachment into an h-BN layer around 700 K. With further temperature increase, free h-BN layers can form, which will modify the properties of the composite.