Effects of strain rate, temperature, and defects on mechanical properties of xgraphene: Molecular dynamics study

Abstract

Xgraphene is a newly proposed derivative of the graphene structure based on first-principles calculations. It is composed of 5–6-7 carbon rings, exhibits unique electrical characteristics, and is projected to be widely employed in high-performance metal-ion battery anodes. In this study, the mechanical properties of xgraphene were systematically evaluated through molecular dynamics simulations, considering factors such as size, strain rate, temperature, and defects, including vacancies, rectangular cracks, and circular voids. Our results demonstrate that xgraphene exhibits anisotropic mechanical behavior, with the armchair direction exhibiting a Young’s modulus 1.0 % higher than the zigzag direction, indicating superior stiffness. The reliability of tensile simulations is influenced by size and strain rate. Variations in temperature, ranging from 1 K to 900 K, lead to reductions in Young’s modulus by 6.4 % along the zigzag and armchair directions. Introducing vacancy defects from 0 to 3 % reduces Young’s modulus by 22 % in the zigzag direction and 20 % in the armchair direction. Increasing the length of rectangular defects from 0 to 4 nm results in a 4.9 % decrease in Young’s modulus along the zigzag and armchair directions. Similarly, increasing the diameter of circular defects from 0 to 4 nm reduces Young’s modulus by 5.4 % along the zigzag direction and 5.3 % along the armchair direction. At later stages of fracture, xgraphene transitions to an amorphous state during tensile strain. This research provides a comprehensive understanding of xgraphene’s mechanical behavior and offers a theoretical basis for its future applications.