skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Melting and Premelting of Carbon Nanotubes

Abstract

We report results of molecular dynamics simulations of melting and premelting of single-walled carbon nanotubes (SWNTs). We found that the traditional critical Lindemann parameter for melting of bulk crystals is not valid for SWNTs. Using the much smaller critical Lindemann parameter for melting of nanoparticles as a criterion, we show that the melting temperature of perfect SWNTs is 4800K. We further show that Stone-Wales defects in a SWNT significantly reduce the melting temperature of atoms around the defects, resulting in premelting of SWNTs at 2600K.

Authors:
 [1];  [2];  [2]
  1. Xiangtan University, Xiangtan Hunan, China
  2. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
931727
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Nanotechnology; Journal Volume: 18; Journal Issue: 28
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 77 NANOSCIENCE AND NANOTECHNOLOGY; CARBON; MELTING; NANOTUBES; MOLECULAR DYNAMICS METHOD; MELTING POINTS

Citation Formats

Zhang, Kaiwang, Stocks, George Malcolm, and Zhong, Jianxin. Melting and Premelting of Carbon Nanotubes. United States: N. p., 2007. Web. doi:10.1088/0957-4484/18/28/285703.
Zhang, Kaiwang, Stocks, George Malcolm, & Zhong, Jianxin. Melting and Premelting of Carbon Nanotubes. United States. doi:10.1088/0957-4484/18/28/285703.
Zhang, Kaiwang, Stocks, George Malcolm, and Zhong, Jianxin. Mon . "Melting and Premelting of Carbon Nanotubes". United States. doi:10.1088/0957-4484/18/28/285703.
@article{osti_931727,
title = {Melting and Premelting of Carbon Nanotubes},
author = {Zhang, Kaiwang and Stocks, George Malcolm and Zhong, Jianxin},
abstractNote = {We report results of molecular dynamics simulations of melting and premelting of single-walled carbon nanotubes (SWNTs). We found that the traditional critical Lindemann parameter for melting of bulk crystals is not valid for SWNTs. Using the much smaller critical Lindemann parameter for melting of nanoparticles as a criterion, we show that the melting temperature of perfect SWNTs is 4800K. We further show that Stone-Wales defects in a SWNT significantly reduce the melting temperature of atoms around the defects, resulting in premelting of SWNTs at 2600K.},
doi = {10.1088/0957-4484/18/28/285703},
journal = {Nanotechnology},
number = 28,
volume = 18,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • No abstract prepared.
  • Nanocomposites based on low molar mass isotactic polypropylene (iPP) and a low concentrations (1-2 wt %) of multiwalled carbon nanotubes (MWCNTs) were studied using thermal analysis, optical and electronic microscopy, and X-ray diffraction/scattering techniques. It was first determined that MWCNT decrease induction time and act as nucleating agents of the iPP crystals during nonisothermal crystallization. One of the consequences of the nucleation effect was that the original spherulitic morphology of iPP was transformed into a fibrillar-like. The corresponding long period of the original well-defined lamellar structure slightly increased suggesting the formation of thicker crystals in samples containing MWCNT. The naturemore » of the {alpha}-iPP crystalline structure was not affected by MWCNT. After nonisothermal crystallization, two melting endotherms were present during thermal scanning of the iPP/MWCNT nanocomposites their proportion changing with the heating rate. After resolving the total DSC signal in its components using MDSC, the overall evolution of such behavior could be explained in terms of the melting/recrystallization mechanism.« less
  • In this work, graphite encapsulated Fe nanoparticles and thin carbon nanotubes (CNTs) supported on the pristine CNTs, respectively, were synthesized using plasma enhanced chemical vapor deposition via efficiently controlling the flow rate of discharging CH{sub 4} and H{sub 2} gas. The properties of the obtained hybrid materials were characterized with superconducting quantum interference and field emission measurements. The results showed that the encapsulated Fe nanoparticles had diameters ranging from 1 to 30 nm, and this hybrid nanocomposite exhibited a ferromagnetic behavior at room temperature. Thin CNTs with an average diameter of 6 nm were attached to the surface of themore » prepared CNTs, which exhibited a lower turn-on field and higher emission current density than the pristine CNTs. The Fe nanoparticles either encapsulated with graphite or used as catalyst for thin CNTs growth were all originated from the pyrolysis of ferrocene. - Graphical abstract: Graphite encapsulated Fe nanoparticles and thin carbon nanotubes supported on the pristine carbon nanotubes, respectively, were synthesized using plasma enhanced chemical vapor deposition.« less
  • This paper presents an experimental investigation on AC conductivity and dielectric behavior of carbon black reinforced high density polyethylene (HDPE-CB) and HDPE-CB filled with multiwalled carbon nanotubes (MWNTs-CB-HDPE) and Polyaniline (PAni) coated MWNTs-CB-HDPE nanocomposites. The electrical properties such as dielectric constant ({epsilon}'), dissipation factor (tan {delta}) and AC conductivity ({sigma}{sub ac}) of nanocomposites have been measured with reference to the weight fraction (0.5 and 1 wt% MWNTs), frequency (75 KHz-30 MHz), temperature (25-90 deg. C) and sea water ageing. The experimental results showed that the increased AC conductivity and dielectric constant of the nanocomposites were influenced by PAni coated MWNTsmore » in HDPE-CB nanocomposites. The value of dielectric constant and tan {delta} decreased with increasing frequency. Further more, above 5 MHz the AC conductivity increases drastically whereas significant effect on tan {delta} was observed in less than 1 MHz.« less
  • Multi-walled carbon nanotubes (MWNTs) supported Pt electrode is prepared by in-situ ion exchange method. X-ray photoelectron spectroscopy (XPS) confirms that compared with the only electrochemical oxidation or chemical oxidation treatment, more carboxylic acid groups are produced on the surface of MWNTs treated by dual-oxidation, which involves both electrochemical oxidation and chemical oxidation. Transmission electron microscopy (TEM) shows that Pt nanoparticles deposited via in-situ ion exchange are highly dispersed on the MWNTs surface. Electrochemical measurements show that the resultant Pt/MWNTs electrode treated by dual-oxidation exhibits the largest electrochemical surface area and the highest activity for oxygen reduction reaction (ORR) among themore » investigated electrodes. This can be attributed to the fact that dual-oxidation treatment produces more carboxylic acid groups at the electroactive sites on MWNTs surface, which results in loading more Pt nanoparticles in the following ion exchange process.« less