Research on the Poisson's Ratio of Black Phosphorene Nanotubes Under Axial Tension.

In this paper, the Poisson's ratio of black phosphorene nanotubes was examined through the molecular dynamics simulation method. Our research discovered that for the armchair black phosphorene nanotubes, the radial strain and the wall thickness strain are negatively linearly correlated with the axial strain, and both the radial Poisson's ratio and the thickness Poisson's ratio are positive. For the zigzag black phosphorene nanotubes, the wall thickness strain is negatively, linearly correlated with the axial strain, while the radial strain has a cubic polynomial function relationship with the axial strain. The thickness Poisson's ratio is positive, while the radial Poisson's ratio is a quantity related to the axial strain. As the axial strain increases, the radial Poisson's ratio progressively diminishes from a positive value and becomes negative upon reaching a specific critical axial strain threshold. During the tensile deformation along the axial direction of the zigzag black phosphorene nanotubes, the radial strain initially decreases before subsequently increasing. Notably, the diameter of the nanotube may even surpass its initial value, demonstrating a radial expansion in response to axial tension.