Elastic and Fracture Properties of Single Walled Pentagraphene Nanotubes

TL;DR

This study explores the mechanical and fracture properties of single-walled pentagraphene nanotubes, revealing their elastic behavior, auxetic properties, and fracture mechanisms through computational simulations.

Contribution

It provides the first detailed analysis of the structural stability, mechanical strength, and fracture patterns of pentagraphene nanotubes using first-principles and molecular dynamics methods.

Findings

Young's modulus of 680-800 GPa

Critical strain of 18-21%

Ultimate tensile stress of 85-110 GPa

Abstract

Membranes of carbon allotropes comprised solely of densely packed pentagonal rings, known as pentagraphene, exhibit negative Poisson's ratio (auxetic behavior) and a bandgap of $3.2$ eV. In this work, we investigated the structural stability, mechanical and fracture properties of nanotubes formed by rolling up pentagraphene membranes, the so-called pentagraphene nanotubes (PGNTs). Single-walled PGNT of three distinct configurations: zigzag, $\alpha$-armchair, and $\beta$-armchair were studied combining first-principles calculations and reactive molecular dynamics simulations. Our results showed Young's modulus values of $680-800 GPa$, critical strain of $18-21\%$, and ultimate tensile stress of $85-110 GPa$. We also observed auxetic behavior. During stretching at room temperature, we observed a transition between $\beta$-armchair to $\alpha$-armchair PGNT close to the critical strain. With relation to fracture patterns, we observed that mechanical failure starts at bonds mostly aligned to the stretching direction and after tube radial collapse.