Reactive Force Field Studies of Large-Deformation of Hybrid Carbon Nanotube-Metal Nanowires
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0963-Q22-04
Reactive Force Field Studies of Large-Deformation of Hybrid Carbon Nanotube-Metal Nanowires Xin Wang1, Ryan King1, and Markus J. Buehler2 1 Mechanical Engineering, Massachusetts Institute of Technology, 77 Mass Ave, Cambridge, MA, 02139 2 Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Mass Ave, Cambridge, MA, 02139 Corresponding author, electronic address [email protected] ABSTRACT We use the ReaxFF reactive force field to model extreme tensile deformation of a (10,10) armchair carbon nanotube. The ReaxFF force field has been developed based on DFT quantum mechanical calculations without any empirical parameters (Duin et al., 2001). We report an analysis of the stress-strain relationship for the elastic and plastic regime, including a description of the microscopic fracture mechanisms. We find Youngís modulus to be around 1 TPa, close to experimental values. Our modeling yields a fracture tensile strain of approximately 30%, with a maximum tensile stress of approximately 300 GPa. Fracture of the CNT originates from formation of 5-7 Stone-Wales-like defects, leading to formation of micro-cracks. We also report preliminary results of straining hybrid CNTs embedding a nickel nanowire. INTRODUCTION Carbon nanotubes (CNTs) constitute a prominent example of nanomaterials, with many potential applications that could take advantage of their unique mechanical, electrical and optical properties [1-7]. A fundamental understanding of the properties of individual CNTs, or assemblies of CNTs in bundles or nanopillars [8], or in conjunction with biological molecules such as DNA [9] may be critical to enable new technologies and to engineer CNT based devices. In particular, the mechanical properties of CNTs are important in many applications. This includes cases in which the primary role of CNTs is not related to their mechanical properties. Nevertheless, a thorough understanding of the mechanical properties is essential to design manufacturing processes or to ensure reliability during operation of devices. The mechanics of carbon nanotubes has been discussed in various articles published over the last decade, both from a continuum and atomistic perspective [10-17]. Failure mechanisms such as fracture nucleation in SWNTs under tension have been discussed using combined continuum-atomistic approaches [10, 11, 18-22]. Full atomistic models have proven to be a quite useful approach in understanding the mechanical behavior of CNTs [10, 11, 21-25]. However, most atomistic modeling was carried using empirical interatomic potentials such as the Tersoff formulation [17], or using quantum mechanical based methods [26]. Here we report an alternative method to describe the mechanics of single wall carbon nanotubes - by using the first principles based reactive force field (ReaxFF). This enables us to model the deformation mechanics of a hybrid nanowire-CNT system.
x 10
11
(10,10) CNT with Ni under tension Ni Pure Carbon
3
X
Stress (Pa)
2.5 2
Pure CNT
1.5
X
1
Hybrid nanowire-CNT
0.5 0
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