Effects of intrinsic strain on the structural stability and mechanical properties of phosphorene nanotubes.

Using molecular dynamics simulations, we explore the structural stability and mechanical integrity of phosphorene nanotubes (PNTs), where the intrinsic strain in the tubular PNT structure plays an important role. It is proposed that the atomic structure of larger-diameter armchair PNTs (armPNTs) can remain stable at a higher temperature, but the high intrinsic strain in the hoop direction renders zigzag PNTs less favorable. The mechanical properties of PNTs, including Young's modulus and fracture strength, are sensitive to the diameter, showing a size-dependence. A simple model is proposed to express Young's modulus as a function of the intrinsic axial strain, which in turn depends on the diameter of the PNTs. In addition, the compressive buckling of armPNTs is length-dependent, and instability modes transitioning from column buckling to shell buckling are observed as the ratio of the diameter/length increases.