On the vibrational behavior of the conventional and hetero-junction carbon nanotubes

On the vibrational behavior of the conventional and hetero-junction carbon nanotubes

The shortcomings and insufficiency in the state-of-the-art investigations about the resonance in the hetero-
junction carbon nanotubes with respect to the number of models and connection types highlight the necessity
of a comprehensive study of the resonance frequency of these nanostructures for applications of these nano-
materials in nanodevices, such as nano-scale electromechanical systems (NEMS) and NEMS-based resonators.
Hence in this study, 50 conventional and 73 hetero-junction middle-length (15 nm) carbon nanotubes, with
armchair-armchair, zigzag-zigzag, armchair-zigzag, armchair-chiral, zigzag-chiral and chiral-chiral connections,
were modeled. Then, the resonance in their structure was comprehensively studied using the finite element
method to present a more reliable estimated range for the natural frequency (fundamental frequency) of hetero-
junction carbon nanotubes. The analysis showed that the natural frequency of conventional carbon nanotubes
lies in the range of 7.09 and 48.75 GHz. An inverse correlation between this quantity and the aspect ratios of the
conventional carbon nanotubes was found, leading to proposing a mathematical relation for the prediction of
such an inverse correlation. The natural frequency of hetero-junction carbon nanotubes oscillated between 4.04
and 60.20 GHz. The results revealed that the natural frequency of hetero-junction carbon nanotubes lies outside
the frequency range of their constructive carbon nanotubes and majorly depends on the boundary conditions and
the difference between the diameters of the connected tubes. Finally, it was observed that the existence of an
armchair carbon nanotube in the structure of hetero-junction models improves their vibrational stabilities.