Investigations Of Thermal Properties Of Carbon Nanotubes And Metal Oxide Nanomaterials Using Raman Spectroscopy And Molecular Dynamics Simulations

Abstract :

Single-walled carbon nanotubes (SWCNTs) are cylindrical tubes formed from covalently bonded carbon atoms and are described mathematically by performing a rolling operation on the honeycomb planar lattice of a single graphite layer. In the current study, we have examined closely the thermal expansion properties of these quasi one-dimensional objects using experimental Raman spectroscopy and Molecular Dynamics simulations. The Raman measurements have been performed employing a Thermo Scientific DXR spectrometer and a heated cell over a range of temperatures (27-200 deg C), while the Molecular Dynamics simulations utilize the powerful and versatile software package - Large-scale Atomic Molecular Massively Parallel Simulator (LAMMPS). The Raman spectra of the SWCNTs were investigated under thermal loading via two methods, namely laser heating and the externally heated cell, in an effort to demonstrate the bond softening and resultant red-shift of the various Raman features of SWCNTs. In addition, metal oxide nanomaterials can provide insight into the changes in structure and properties that result from the chemisorption of oxygen in the lattice and the way energy is stored in nanomaterials. We have examined the characteristics of graphitic and metal oxide nanomaterials using Resonant Raman Spectroscopy at 514, 532 and 780 nm laser excitations using the DXR Smart Raman spectrometer and a Renishaw inVia Raman Microscope. Computational atomistic analysis of the associated phonon thermodynamics has been performed with the goal of determining the effect that temperature has on the vibrational frequencies of the nanomaterials. In many future applications of graphitic nanomaterials, the electronic devices will have to endure high temperatures during manufacturing and/or operation, whereby the induced strain and thermal expansion characteristics may serve as significant quality/reliability control factors.Intriguing results from both experimental measurements and simulation studies help to shed light on the thermal properties of SWCNTs and metal oxide nanomaterials that have important ramifications for their use in electronic devices.