Temperature, strain rate, and point vacancy dependent anisotropic mechanical behaviors of titanium carbide (Ti3C2) MXene: A molecular dynamics study

Abstract

MXenes, one of the recognizable examples of modern 2D materials, are sparking tremendous research interest because of their distinctive structural, electrical, and electrochemical properties. This study utilized classical molecular dynamics simulation to investigate temperature, strain rate, and point vacancy-dependent mechanical behaviors for both armchair and zigzag orientations of the Ti3C2 MXene using Tersoff style bond order potential. The elastic modulus of ∼155.76 GPa and fracture strain of ∼0.263 were obtained along the zigzag direction at 300 K temperature, 5.58 % and 28.29 % greater than those obtained along the armchair alignment. However, a superior tensile strength of ∼34.08 GPa was observed along the armchair orientation as opposed to ∼29.08 GPa in the zigzag direction at 300 K temperature. As the temperature rises, it was observed that fracture strength and strain both exhibit a decreasing tendency, whereas increments in strain rates cause an increasing trend. However, we observed that temperature and strain rates barely affect the elastic modulus, which agrees with the literature data. Radial distribution functions were calculated for all pair interactions to make the temperature effect more comprehensible. It was demonstrated that C, Ti, and random point vacancies have significant adverse effects on elastic modulus, fracture strength, and failure strain because of their powerful symmetry-breaking effect. With increasing concentrations of any point vacancies, rapidly declining elastic modulus, fracture strength, and failure strain were perceived. Titanium vacancies were observed to have a more significant influence on mechanical behavior, even though carbon vacancies were more likely to develop with less formation energy. The outcomes of this work deliver a clear overview of the mechanical behavior of Ti3C2 in various aspects of the environment and will shed light on the potential implementation in electrochemical sensing or energy devices.