Mechanical Properties of Atomically Thin Boron Nitride and the Role of Interlayer Interactions

TL;DR

This study reveals that atomically thin boron nitride nanosheets are exceptionally strong and their mechanical properties are less affected by thickness compared to graphene, due to different interlayer interactions.

Contribution

The paper provides new insights into the mechanical behavior of BN nanosheets and highlights the role of interlayer interactions in their strength, contrasting with graphene.

Findings

BN nanosheets are among the strongest electrically insulating 2D materials.

Mechanical strength of BN is insensitive to thickness increases.

Interlayer interactions significantly influence mechanical properties.

Abstract

Atomically thin boron nitride (BN) nanosheets are important two-dimensional nanomaterials with many unique properties distinct from those of graphene, but the investigation of their mechanical properties still greatly lacks. Here we report that high-quality single-crystalline mono- and few-layer BN nanosheets are one of the strongest electrically insulating materials. More intriguingly, few-layer BN shows mechanical behaviors quite different from those of few-layer graphene under indentation. In striking contrast to graphene, whose strength decreases by more than 30% when the number of layers increases from 1 to 8, the mechanical strength of BN nanosheets is not sensitive to increasing thickness. We attribute this difference to the distinct interlayer interactions and hence sliding tendencies in these two materials under indentation. The significantly better mechanical integrity of BN nanosheets makes them a more attractive candidate than graphene for several applications, e.g. as mechanical reinforcements.