Tension-Induced Phase Transformation and Anomalous Poisson Effect in Violet Phosphorene

Abstract

Two-dimensional violet phosphorene (VP) nanosheets are promising semiconductor materials with unique cross structures distinct from those of their allotropes such as black phosphorene and blue phosphorene, but their mechanical behaviors remain almost unexplored. By using the first-principles calculations, in this paper we investigate the mechanical behaviors of monolayer, bilayer, and bulk VP under uniaxial tension. A phase transformation from the open-pore phase to closed-pore phase is observed in VP structures when under a specific tensile strain. It is revealed that the phase transformation is attributed to the competition between the rotation and elongation of sub-nano rods in VP structures during the loading process. Due to the phase transformation, the in-plane Poissons ratio of monolayer VP can become greater than 1.2, while the bulk VP possesses a negative out-of-plane Poissons ratio with a magnitude up to -0.3 at a certain strain. These results indicate that Poisson effects in VP are superior to those in any other existing two-dimensional materials. In addition, based on the tensor analysis of elastic constants, a strong mechanical anisotropy is observed in VP structures both before and after the phase transformation. Besides the mechanical properties, the band gap of all VP structures decreases as the applied tensile strain increases, which can eventually transform into the metallic state prior to their fracture. The combination of unique phase transformation, anomalous Poisson effect, strong mechanical anisotropy and tunable electronic properties render VP be a novel nanoscale metamaterial with multifunctional applications.

Anisotropic mechanical properties of monolayer fullerene network: An interplay between two types of interfullerene bonds

“…However, not enough attention has been paid to the mechanics of 2D C60 polymers, which should play a key role in determining the structural integrity of the recently synthesized monolayer qHP C60. Moreover, the mechanical properties of monolayer qHP C60 are also of great importance for the proper functioning of qHP C60-based devices, since the strain engineering is usually an efficient method to modify the properties of 2D materials [22][23][24][25]. Thus, the successful application of monolayer qHP C60-based electronic devices crucially relies on a comprehensive understanding of the component monolayer qHP C60.…”