Tensile and compressive behaviors of open-tip carbon nanocones under axial strains
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Chin-Hsiang Chenga) and Yang-Ping Lin Department of Aeronautics and Astronautics, National Cheng Kung University, Tainan 70101, Taiwan (Received 29 January 2011; accepted 2 May 2011)
The influences of temperature, cone height, and apex angle on the tensile and compressive behaviors of open-tip carbon nanocones (CNCs) under axial strains were examined. The tensile failure strain and failure load of the CNC were found to decline evidently as the system temperature increases. The average failure strain decreases with the growth in the cone height. Concerning compressive behaviors, the critical strain and critical load of the CNC reduce manifestly with the increase in the system temperature and the apex angle. As the cone height grows, the critical strain decreases evidently but the critical load has no obvious change. The buckling mode does not have much variation when the temperature increases. It displays a more distorted buckling pattern with the growth in the cone height and transfers from an axisymmetric pattern to an unsymmetrical and more warped pattern when the apex angle expands.
I. INTRODUCTION
Since the finding of carbon nanotubes (CNTs) by Iijima1 in 1991, owing to their extraordinary and distinguished properties, researchers have taken much interest in exploring the immature feature and potential applications of the CNTs and also of the related carbon nanostructures.2 Carbon nanocones (CNCs) are one of such nanostructures that have structures similar to those of the CNTs. Ge and Sattler3 first proposed that there have been five types of CNCs with apex angles of 19.2, 38.9, 60, 86.6, and 123.6°, respectively. Later, Krishnan et al.4 verified the existence of the five types of CNCs by experimental methods. Recently, Naess et al.5 also studied the structure and morphology of the five types of CNCs with the aid of transmission electron microscopy, synchrotron x-ray, and electron diffraction. With proper control of the synthetic conditions, it was found that open-tip CNCs (with their tips truncated) could be synthesized.6–8 For example, Terrones et al.7 used a chemical vapor deposition (CVD) method to synthesize open-tip CNCs and discussed the evidence of having different apex angles in the CNCs. Later, the open-tip CNCs were proved to have similar structures and the same apex angles as the closed CNCs.9 Moreover, analogous to CNTs, the CNCs can also be classified as single-walled and multiwalled CNCs according to the number of layers comprising the nanocones.10–12 Mass production of CNCs a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2011.160 J. Mater. Res., Vol. 26, No. 13, Jul 14, 2011
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is possible with the assistance of plasma. For example, Tsakadze et al.13 used a plasma-assisted chemical vapor deposition method to grow uniform CNCs arrays. Their group also proposed a plasma-assisted model for the growth of sharp-tip and flat-tip CNCs arrays.14 Because CNCs have their special cone shapes, their tip structur
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