Multi-Walled Carbon Nanotubes Synthesized by Methane Pyrolysis: Structure and Magnetic Properties

The structure and magnetic properties of multi-walled carbon nanotubes produced by catalytic pyrolysis of methane have been investigated by means of mutually complementary physical methods. The average sizes and number of carbon layers forming nanotubes, smearing of the density of states near the Fermi level, degeneracy temperature of gas of extrinsic current carriers, concentrations of localized spins and extrinsic two-dimensional current carriers have been determined. The conclusion has been drawn that ferromagnetic nanoparticles are present in the inner regions of nanotubes, including their tubular cavities. The difference in electronic structure near the Fermi level for carbon nanotubes and ordered graphite has been revealed. The possible reason is that the electronic states near zigzag-type sites of ends as well as edges of linear structural defects in nanotubes make greater contribution to the spectrum than that from similar sites of graphite.

Download Full-text

Synergy Effects in Electromagnetic Properties of Phosphate Ceramics with Silicon Carbide Whiskers and Carbon Nanotubes

Applied Sciences ◽

10.3390/app9204388 ◽

2019 ◽

Vol 9 (20) ◽

pp. 4388 ◽

Cited By ~ 2

Author(s):

Artyom Plyushch ◽

Jan Macutkevič ◽

Polina Kuzhir ◽

Aliaksei Sokal ◽

Konstantin Lapko ◽

...

Keyword(s):

Carbon Nanotubes ◽

Silicon Carbide ◽

Wide Frequency Range ◽

Electromagnetic Properties ◽

Aluminium Phosphate ◽

Silicon Carbide Whiskers ◽

Synergy Effects ◽

Multi Walled Carbon Nanotubes ◽

The Difference ◽

Walled Carbon Nanotubes

Hybrid composite materials based on an aluminium phosphate matrix with silicon carbide whiskers and multi-walled carbon nanotubes were studied in a wide frequency range (20 Hz to 36 GHz). It was demonstrated, that the addition of the silicon carbide whiskers enhances the dielectric permittivity and conductivity. This was explained by the difference in tunnelling parameters. Hybrid ceramics with nanotubes and whiskers also exhibits substantially improved electromagnetic shielding properties. The hybrid ceramics with 10 wt. % silicon carbide whiskers and a 1 mm thick 1.5 wt. % carbon nanotube layer, show higher than 50% absorption of electromagnetic radiation.

Download Full-text

Mechanical, dielectric, and magnetic properties of the silicone elastomer with multi-walled carbon nanotubes as a nanofiller

Polymer Engineering & Science ◽

10.1002/pen.20833 ◽

2007 ◽

Vol 47 (9) ◽

pp. 1396-1405 ◽

Cited By ~ 39

Author(s):

Il-Seok Park ◽

Kwang J. Kim ◽

Jae-Do Nam ◽

Joonsoo Lee ◽

Woosoon Yim

Keyword(s):

Carbon Nanotubes ◽

Magnetic Properties ◽

Silicone Elastomer ◽

Multi Walled Carbon Nanotubes ◽

Walled Carbon Nanotubes

Download Full-text

Effects of structural defects on strength and fracture properties of multi-walled carbon nanotubes

Transactions of the JSME (in Japanese) ◽

10.1299/transjsme.16-00283 ◽

2017 ◽

Vol 83 (847) ◽

pp. 16-00283-16-00283 ◽

Cited By ~ 4

Author(s):

Itaru TAMAKI ◽

Keiichi SHIRASU ◽

Takamichi MIYAZAKI ◽

Go YAMAMOTO ◽

Raman BEKAREVICH ◽

...

Keyword(s):

Carbon Nanotubes ◽

Structural Defects ◽

Fracture Properties ◽

Multi Walled Carbon Nanotubes ◽

Walled Carbon Nanotubes

Download Full-text

Defect-induced vibrational response of multi-walled carbon nanotubes using resonance Raman spectroscopy

Journal of Materials Research ◽

10.1557/jmr.2005.0414 ◽

2005 ◽

Vol 20 (12) ◽

pp. 3368-3373 ◽

Cited By ~ 44

Author(s):

S.A. Curran ◽

J.A. Talla ◽

D. Zhang ◽

D.L. Carroll

Keyword(s):

Carbon Nanotubes ◽

Raman Spectroscopy ◽

Acid Treatment ◽

Defect Formation ◽

Double Resonance ◽

Resonance Raman ◽

The Body ◽

Structural Defects ◽

Multi Walled Carbon Nanotubes ◽

Walled Carbon Nanotubes

We systematically introduced defects onto the body of multi-walled carbon nanotubes through an acid treatment, and the evolution of these defects was examined by Raman spectroscopy using different excitation wavelengths. The D and D′ modes are most prominent and responsive to defect formation caused by acid treatment and exhibit dispersive behavior upon changing the excitation wavelengths as expected from the double resonance Raman (DRR) mechanism. Several weaker Raman resonances including D″ and L1 (L2) + D′ modes were also observed at the lower excitation wavelengths (633 and 785 nm). In addition, specific structural defects including the typical pentagon-heptagon structure (Stone–Wales defects) were identified by Raman spectroscopy. In a closer analysis we also observed Haeckelite structures, specifically Ag mode response in R5,7 and O5,6,7.

Download Full-text

Magnetic Properties of Multi-Walled Carbon Nanotubes

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2009.441 ◽

2009 ◽

Vol 9 (3) ◽

pp. 1956-1963 ◽

Cited By ~ 16

Author(s):

Lun-Wei Chang ◽

Juh-Tzeng Lue

Keyword(s):

Carbon Nanotubes ◽

Magnetic Properties ◽

Multi Walled Carbon Nanotubes ◽

Walled Carbon Nanotubes

Download Full-text

Study on Dielectric and Magnetic Properties of MWCNTs/Polyester Composites

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.815.188 ◽

2015 ◽

Vol 815 ◽

pp. 188-192

Author(s):

Y.S. Lee ◽

F. Malek ◽

E.M. Cheng ◽

Wei Wen Liu ◽

Kok Yeow You ◽

...

Keyword(s):

Carbon Nanotubes ◽

Magnetic Properties ◽

Dielectric Properties ◽

Rectangular Waveguide ◽

The Real ◽

Multi Walled Carbon Nanotubes ◽

Polyester Composites ◽

Walled Carbon Nanotubes ◽

Ku Band ◽

Dielectric Conductivity

This paper is to study the dielectric properties, magnetic properties, and dielectric conductivity of Multi-walled carbon nanotubes (MWCNTs) and polyester (PE) composites. The composites with different amount of MWCNTs (5-15%) have been studied in the Ku-Band range (12.4-18 GHz). The rectangular waveguide (WR-62) was used to measure the dielectric properties and magnetic properties of the samples. The results show the dielectric properties and conductivity of MWCNTs/PE composites is increasing with the MWCNTs filler increases. The real part of dielectric properties values increase from 5.5 to 26.6 with increasing the MWCNTs loading from 5 % to 15 %. The increasing of MWCNTs filler in the MWCNTs/PE composites does not effects on magnetic properties, the real part and imaginary part of magnetic properties are approximate to 1 and 0. The highest conductivity of 15 % MWCNTs loading is reach to 11.02 (S/m) at 18 GHz. Keywords: composites, dielectric properties, magnetic properties, conductivity

Download Full-text

STM/STS investigation of carbon nanotubes deposited on Bi2Te3 surface

Open Physics ◽

10.2478/s11534-009-0006-z ◽

2009 ◽

Vol 7 (2) ◽

Cited By ~ 2

Author(s):

Maciej Bazarnik ◽

Maciej Cegiel ◽

Piotr Biskupski ◽

Monika Jazdzewska ◽

SÅ‚awomir Mielcarek ◽

...

Keyword(s):

Carbon Nanotubes ◽

Electronic Structure ◽

Scanning Tunneling Microscopy ◽

Structural Defects ◽

Scanning Tunneling ◽

Narrow Gap ◽

Tunneling Microscopy ◽

Multi Walled Carbon Nanotubes ◽

Walled Carbon Nanotubes ◽

Walled Cnts

AbstractThis paper reports our scanning tunneling microscopy and spectroscopy (STM/STS) study of double-walled and multi-walled carbon nanotubes (CNTs) of different diameter deposited on Bi2Te3 (narrow gap semiconductor). The approximate diameter of the studied double-walled and multi-walled CNTs was 2 nm and 8 nm, respectively. Crystalline Bi2Te3 was used as a substrate to enhance the contrast between the CNTs and the substrate in the STS measurements performed to examine peculiarities of CNT morphology, such as junctions, ends or structural defects, in terms of their electronic structure.

Download Full-text