Tuesday  |  Conference Center B  |  09:20 AM–10:00 AM

#13599, An Experimental-Computational Atomistic Investigation of Fracture in 2D Materials – A Case Study on MoSe2

2D materials such as transition metal dichalcogenides (TMDCs) and MXenes are being widely used in applications ranging from piezoelectric nano-resonators to semiconductors in optoelectrical devices to electrode material in batteries. In all these applications a fundamental understanding of mechanical properties is needed. However, there is scarcity of literature reports on experimental and computational modeling of failure. In this presentation, we will report an integrated experimental-numerical framework that overcome current experimental limitations. Specifically, we will discuss crack tip deformation fields, obtained from high-resolution transmission electron microscope images (HRTEM), together with calculation of atomic displacement fields, strain/stress fields, and corresponding J-integral [1]. The idea is to quantify the toughness of monolayer MoSe2 and examine the range of applicability of linear elastic fracture mechanics. We will also report atomistic simulations performed using a recently parameterized Tersoff potential [2], which has been optimized to accurately describe bonds dissociation and reconfiguration, both important processes occurring at crack tips. We found that the experimental and molecular dynamics computed J~3.24 (±0.5) N/m are in excellent agreement. Based on this finding, we numerically investigated the effect of mono-selenium vacancies on toughness. Likewise, we investigated other defect types, previously observed in high resolution TEM studies, such as monomolybdenium or selenium-line vacancies. These studies provide a road map for integrating in situ experiments and molecular modeling aiming to provide accurate predictions of mechanical properties and failure of 2D materials.

References:
[1] Rice, J. R. (June 1, 1968). "A Path Independent Integral and the Approximate Analysis of Strain Concentration by Notches and Cracks." ASME. J. Appl. Mech. June 1968; 35(2): 379–386.

[2] Zhang, X., Nguyen, H., Paci, J.T. et al. “Multi-objective parametrization of interatomic potentials for large deformation pathways and fracture of two-dimensional materials.” NPJ Computational Materials, 7, 113 (2021).

Horacio Espinosa   Northwestern University
Xu Zhang   Northwestern University
Hoang Nguyen   Northwestern University