scholarly journals Feedstock Diffusion and Decomposition in Aligned Carbon Nanotube Arrays

2009 ◽  
Author(s):  
Rong Xiang ◽  
Erik Einarsson ◽  
Junichiro Shiomi ◽  
Shigeo Maruyama
Keyword(s):  
Carbon Nanotube ◽  
Carbon Source ◽  
Flow Rate ◽  
Chemical Vapor ◽  
Mean Free Path ◽  
Diffusion Limit ◽  
Diffusion Resistance ◽  
Diffusion Controlled ◽  
Cnt Arrays ◽  
Growth Deceleration

Feedstock diffusion and decomposition in the root growth of aligned carbon nanotube (CNT) arrays is discussed. A non-dimensional modulus is proposed to differentiate catalyst-poisoning controlled growth deceleration from one which is diffusion controlled. It is found that, at current stage, aligned multi-walled carbon nanotube (MWNT) arrays are usually free of feedstock diffusion resistance. However, for single-walled carbon nanotube (SWNT) arrays, since the inter-tube distance is much smaller than the mean free path of carbon source (ethanol here), high diffusion resistance is significantly limiting the growth rate. The method presented here is also able to predict the critical lengths in different chemical vapor deposition (CVD) processes from which CNT arrays begin to meet this diffusion limit, as well as the possible solutions to this diffusion caused growth deceleration. The diffusion of carbon source inside of an array becomes more important when we found ethanol undergoes severe thermal decomposition at the reaction temperature. This means, in a typical alochol CVD, hydrocarbons and radicals decomposed from ethanol may collide and react with the outer walls of SWNTs before reaching catalyst particles. We found when flow rate is low and ethanol is thoroughly decomposed, the produced SWNTs contain more soot structures than the SWNTs obtained at higher ethanol flow rate. Understanding the mass transport and reaction inside a SWNT array is helpful to synthesize longer and cleaner SWNTs.

scholarly journals Feedstock Diffusion and Decomposition in Aligned Carbon Nanotube Arrays

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
Rong Xiang ◽  
Erik Einarsson ◽  
Junichiro Shiomi ◽  
Shigeo Maruyama
Keyword(s):  
Carbon Nanotube ◽  
Carbon Source ◽  
Flow Rate ◽  
Chemical Vapor ◽  
Mean Free Path ◽  
Diffusion Limit ◽  
Diffusion Resistance ◽  
Multiwalled Carbon ◽  
Cnt Arrays ◽  
Growth Deceleration

Feedstock diffusion and decomposition in the root growth of aligned carbon nanotube (CNT) arrays is discussed. A nondimensional modulus is proposed to differentiate catalyst poisoning controlled growth deceleration from one which is diffusion controlled. It is found that, at present, aligned multiwalled carbon nanotube (MWNT) arrays are usually free of feedstock diffusion resistance. However, for single-walled carbon nanotube (SWNT) arrays, since the intertube distance is much smaller than the mean free path of carbon source (ethanol here), high diffusion resistance in some currently available samples is significantly limiting the growth rate. The method presented here is also able to predict the critical lengths in different chemical vapor deposition (CVD) processes from which CNT arrays begin to meet this diffusion limit, as well as the possible solutions to this diffusion caused growth deceleration. The diffusion of carbon source inside of an array becomes more important when we found ethanol undergoes severe thermal decomposition at the reaction temperature. This means, in a typical alcohol CVD, hydrocarbons and radicals decomposed from ethanol may collide and react with the outer walls of SWNTs before reaching catalyst particles. When flow rate is low and ethanol is thoroughly decomposed, the produced SWNTs contain more soot structures than the SWNTs obtained at higher ethanol flow rate. Understanding the mass transport and reaction inside a SWNT array is helpful to synthesize longer and cleaner SWNTs.

scholarly journals Synthesis of High-Quality Carbon Nanotube Arrays without the Assistance of Water

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Yongfeng Luo ◽  
Xinjun Wang ◽  
Mengdong He ◽  
Xi Li ◽  
Hong Chen
Keyword(s):  
Carbon Nanotube ◽  
Carbon Source ◽  
Chemical Vapor ◽  
Deposition Process ◽  
Nanotube Arrays ◽  
High Quality ◽  
Nanotube Array ◽  
Carbon Nanotube Arrays ◽  
Cnt Arrays ◽  
First Time

Long and high-quality carbon nanotube (CNT) arrays have been synthesized through a chemical vapor deposition process. The Fe/Al2O3on silicon was used as the catalyst, ethylene as the carbon source, and a gas mixture of Ar and H2gases as the carrying gas. It is found for the first time that the high-quality and superlong carbon nanotube array can be improved by varying the content of hydrogen and carbon source.

Carbon nanotube cathodes covered on the cylindrical surface of a fiber

RSC Advances ◽  
2015 ◽  
Vol 5 (22) ◽  
pp. 17049-17053 ◽  
Author(s):  
Xianqi Wei ◽  
Youzhang Zhu ◽  
Xianjun Xia ◽  
Xiaoli Wang ◽  
Weihuan Liu ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Carbon Nanotube ◽  
Field Emission ◽  
Vapor Deposition ◽  
Cylindrical Surface ◽  
Chemical Vapor ◽  
Quartz Optical Fiber ◽  
Cnt Arrays ◽  
Field Emission Cathodes ◽  
Waveguide Surface

Carbon nanotube (CNT) arrays were synthesized on the cylindrical waveguide surface of a quartz optical fiber by chemical vapor deposition (CVD) to serve as field emission cathodes.

Recent Research Progress of Carbon Nanotube Arrays Prepared by Plasma Enhanced Chemical Vapor Deposition Method

2016 ◽  
Vol 852 ◽  
pp. 308-314
Author(s):  
Er Xiong Ding ◽  
Hong Zhang Geng ◽  
Li He Mao ◽  
Wen Yi Wang ◽  
Yan Wang ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Carbon Nanotube ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Research Progress ◽  
Chemical Vapor Deposition Method ◽  
In Situ Fabrication ◽  
Microwave Pecvd ◽  
Cnt Arrays ◽  
The Moment

Preparing carbon nanotube (CNT) arrays by plasma enhanced chemical vapor deposition (PECVD) method can dramatically reduce the deposition temperature, which makes it possible for in-situ fabrication of CNT-based nanoelectronic devices. In this paper, up to date research progress of CNT arrays prepared by PECVD method was presented, including radio frequency PECVD, direct current PECVD and microwave PECVD. Then, morphology and quality of CNT arrays were compared. In the end, we analyzed the possible challenges encountered through CNT array preparation by PECVD method at the moment and in the future.

Preparation and Characterization of Aligned Carbon Nanotube Fibers

2013 ◽  
Vol 275-277 ◽  
pp. 1794-1797
Author(s):  
Yong Feng Luo ◽  
Cui Zhou ◽  
Xi Li ◽  
Shui Li ◽  
Zhong Zhi Sheng
Keyword(s):  
Carbon Nanotube ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Deposition Process ◽  
High Quality ◽  
Dry Spinning ◽  
Excellent Mechanical Property ◽  
Cnt Arrays ◽  
Carbon Nanotube Fibers

High-quality carbon nanotube (CNT) arrays have been synthesized through a chemical vapor deposition process. The Fe/Al2O3 on silicon was used as the catalyst, ethylene as the carbon source, and a mixture gas of Ar and H2 gases as the carrying gas. With spinnable CNT arrary as initial materials, aligned carbon nanotube fibers were continuously fabricated by dry spinning. And then we study the excellent mechanical property of the carbon nanotube fibers.

Carbon Nanotube Array Thermal Interfaces on Chemical Vapor Deposited Diamond

2007 ◽  
Author(s):  
Baratunde A. Cola ◽  
Xianfan Xu ◽  
Timothy S. Fisher
Keyword(s):  
Carbon Nanotube ◽  
Diamond Film ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Photoacoustic Technique ◽  
Nanotube Array ◽  
Carbon Nanotube Array ◽  
Chemical Vapor Deposited ◽  
Cnt Arrays ◽  
Film Interface

Carbon nanotube (CNT) arrays have been directly synthesized on plasma-enhanced chemical vapor deposited diamond films in the same growth chamber. The diamond films were grown using a bias-enhanced nucleation technique that produces relatively smooth and flat films. The thermal resistances of the CNT array/diamond film interface were measured using a photoacoustic technique to be approximately 12 mm2·K/W at moderate pressures.

Origins of Height Distribution within Carbon Nanotube Arrays

2015 ◽  
Vol 32 ◽  
pp. 17-24 ◽  
Author(s):  
Yang Li ◽  
Ru Li ◽  
Hao Zhang ◽  
Min Luo ◽  
Yong Yi Zhang ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Carbon Source ◽  
Height Distribution ◽  
Competitive Effect ◽  
Pyrolysis Products ◽  
Subsequent Formation ◽  
Small Areas ◽  
Moderate Growth ◽  
Carbon Nanotube Arrays ◽  
Cnt Arrays

We investigated the phenomenon of non-uniform height distribution within CVD-grown carbon nanotube (CNT) arrays. This phenomenon is related to the activity of the catalyst which is affected by the deposition of the carbon source and the subsequent formation of pyrolysis products on the catalyst. We developed a model that considers the effects of deposition of the carbon source as well as the fact that the pyrolysis products also accumulate at the edges of CNT arrays. This model also illustrates that carbon source deposition results in moderate growth over large areas, whereas the pyrolysis products hinder growth significantly over small areas. Together, the two have a competitive effect on CNT growth and bring about the height distribution feature.

Optimization of Super-Long CNT Forests Growth on Conductive Substrate by Water Assisted CVD

2014 ◽  
Vol 496-500 ◽  
pp. 536-540
Author(s):  
Peng Bo Wang ◽  
De Yang Xu ◽  
Li Ning Sun
Keyword(s):  
Chemical Vapor Deposition ◽  
Carbon Nanotube ◽  
Optimum Condition ◽  
Flow Rate ◽  
Growth Temperature ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Conductive Substrate ◽  
Vertically Aligned

Water assisted chemical vapor deposition (CVD) is used widely to synthesize super long, vertically aligned, densely packed carbon nanotube (CNT) forests. Various water assisted CVD parameters give the important influence on the quality of CNT forests. In this paper, several main parameters in water assisted CVD are optimized, such as the flow rate of H2, the content of water and growth temperature. Furthermore, growth on the conductive substrate is also studied by water assisted CVD. Under optimum condition with 10 minutes growth, the length of CNT forests could be 815 μm on silicon substrate and 369 μm on conductive substrate.

Thermal Contact Conductance Enhancement With Carbon Nanotube Arrays

2004 ◽  
Author(s):  
Jun Xu ◽  
Timothy S. Fisher
Keyword(s):  
Carbon Nanotube ◽  
Thermal Contact ◽  
High Vacuum ◽  
Multiwall Carbon Nanotubes ◽  
Chemical Vapor ◽  
Radiation Shielding ◽  
Thermal Contact Conductance ◽  
Metal Foil ◽  
Contact Conductance ◽  
Cnt Arrays

The present work reports on an experimental study of carbon nanotube (CNT) arrays used for thermal contact conductance enhancement. Multiwall carbon nanotubes were synthesized directly on silicon wafers using plasma-enhanced chemical vapor deposition. Thermal contact conductance was experimentally measured with a steady-state contact conductance technique. To reduce heat losses and experimental uncertainty, testing occurred in a high-vacuum environment with radiation shielding, and temperature measurements were made with an infrared camera. In addition, results from other thermal interface materials (phase change material and metal foil) are presented, and the performance of combinations of these materials with CNT arrays are also reported.

Controlled Growth and Supercapacitive Behaviors of CVD Carbon Nanotube Arrays

2011 ◽  
Vol 688 ◽  
pp. 11-18 ◽  
Author(s):  
Dan Dan Zhao ◽  
Zhi Yang ◽  
Hao Wei ◽  
Ya Fei Zhang
Keyword(s):  
Carbon Nanotube ◽  
Particle Density ◽  
Chemical Vapor ◽  
Growth Time ◽  
Controlled Growth ◽  
Si Substrate ◽  
Graphene Layers ◽  
Wide Range ◽  
Cnt Arrays ◽  
Vertically Aligned

Low-pressure chemical vapor deposition (LP-CVD) technique has been utilized for controlled growth of carbon nanotube (CNT) arrays on silicon wafers. The tube-diameters of CNTs and the number of graphene layers are controlled by varying the thickness of catalyst films. The catalyst particle density and the growth conditions such as the ambient gas and the local environment are all crucial for the formation of vertically aligned CNT arrays. The length of CNT arrays can be controlled by altering the growth time. In addition, the supercapacitive properties of CNT arrays with various morphologies growing on different current collectors have been investigated using a less corrosive 0.5 M Na2SO4aqueous solution as the electrolyte. Vertically aligned CNT arrays on Ti-Si substrate produce a higher capacitance compared to randomly oriented CNTs on the same current collector. Furthermore, Ni foam enables better utilization of active materials than Ti-Si substrate. CNT arrays electrodes fabricated by this simple, low cost approach demonstrate stable and consistent capacitor behaviors for a wide range of scan rates. Moreover, CNT arrays electrodes provide better platform for further integration with transitional metal oxide, via simple sputtering or electrodeposition technique, to enhance the supercapacitive performance.

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