Abstract
Carbon nanotube based multi-terminal junction configurations are of great interest because of the potential aerospace and electronic applications. Multi-terminal carbon nanotube junction has more than one carbon nanotube meeting at a point to create a 2D or 3D structure. Accurate atomistic models of such junctions are essential for characterizing their thermal, mechanical and electronic properties via computational studies. In this work, computational methodologies that uses innovative Computer-Aided Design (CAD) based optimization strategies and remeshing techniques are presented for generating such topologically reliable and accurate models of complex multi-terminal junctions (called 3-, 4-, and 6-junctions). This is followed by the prediction of structure-property relationship via study of thermal conductivity and mechanical strength using molecular dynamics simulations. We observed high degradation in the thermal and mechanical properties of the junctions compared to pristine structures which is attributed to high concentration of non-hexagonal defects in the junction. Junctions with fewer defects have better thermal transport capabilities and higher mechanical strengths, suggesting that controlling the number of defects can significantly improve inherent features of the nanostructures.
Highlights
Carbon based nano-materials have excellent mechanical (Chopra et al, 1995; Iijima et al, 1996), thermal (Che et al, 2000) and electrical (Bandaru, 2007) properties, yet are extremely lightweight that makes them ideal for nanoscale system design and applications (Suehiro et al, 2003; Zhang et al, 2006; Jensen et al, 2007; Mundra et al, 2014)
In our previous communication (Nakarmi et al, 2018), we presented an efficient methodology to create topologically accurate three terminal (3T-) junction models based on computer-aided design (CAD) based optimization and re-meshing techniques that uses dual (Patanè and Spagnuolo, 2003) of the regular hexagonal mesh
In multi-terminal junctions, thermal transport is expected to be governed by the number of connected arms, defects types, and their distribution around the junction, as well as the size and type of Carbon nanotubes’ (CNTs) that form the junction
Summary
Carbon based nano-materials (graphene, nanotubes, and carbon fibers) have excellent mechanical (Chopra et al, 1995; Iijima et al, 1996), thermal (Che et al, 2000) and electrical (Bandaru, 2007) properties, yet are extremely lightweight that makes them ideal for nanoscale system design and applications (Suehiro et al, 2003; Zhang et al, 2006; Jensen et al, 2007; Mundra et al, 2014). Carbon nanotubes’ (CNTs’) -cylindrical honeycomb structures made up of Carbon atoms bonded in sp hybridization, are popular for their high thermal conductivity, strength, modulus, and aspect ratio They have been used for the fabrication of nano electronic devices (Yao et al, 1999; Chernozatonskii, 2003), composites (Haggenmueller et al, 2000) and cooling fins (Kordás et al, 2007). In a 3D CNT based structural forms, they are often observed as interconnecting nodes (junctions) of varying characteristics These junctions have fascinating features that are different from the pristine CNTs (Wei and Liu, 2008) and are suitable for constructing nano-level building blocks with modulated mechanical, thermal, and electrical properties. The MD simulations are carried out using LAMMPS (Plimpton et al, 2007) and OVITO (Stukowski, 2010) is used for nanostructure visualization
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