Well aligned nanotubes with diameter of 30—50 nm have been synthesized on a porous alumina template by microwave plasma enhanced chemical vapor deposition (MW PECVD). By this means, the control over either diameter o...Well aligned nanotubes with diameter of 30—50 nm have been synthesized on a porous alumina template by microwave plasma enhanced chemical vapor deposition (MW PECVD). By this means, the control over either diameter or length of the nanotubes could be realized. The hollow structure and vertically aligned features have been verified by scanning electron and transmission electron microscopic images. In comparison with the reported fabrication methods, lower synthesis temperature (below 520 ℃) and simpler process (no negative dc bias applied) have been achieved, which could be of great importance for both theoretical research and pratical applications.展开更多
Among the three main methods for the s ynthesis of carbon nanotubes(CNTs ),chemical vapor deposition(CVD)has received a great deal of attentio n since CNTs can be synthesized at sig nificantly low temperature.Plasma c...Among the three main methods for the s ynthesis of carbon nanotubes(CNTs ),chemical vapor deposition(CVD)has received a great deal of attentio n since CNTs can be synthesized at sig nificantly low temperature.Plasma chemical vapor deposition me thods can synthesize CNTs at lower te mperature than thermal CVD.But in th e usual catalytic growth of CNTs by CVD,CNTs are often tangled together and have some defects.These will limit t he property research and potential applications.How to synthesize the str aight CNTs at low temperature become s a challenging issue.In this letter,s traight carbon nanotube(CNT)films were achieved by microwave pla sma chemical vapor deposition(MWPCVD)catalyzed by round Fe-Co-Ni alloy particles on Ni substrate at 610℃.It wa s found that,in our experimental condition,the uniform growth rate along the circumference of round alloy particles plays a very important role in the gro wth of straight CNT films.And because the substrate is conducting,the straight CNT films grown at low temperature ma y have the benefit for property research and offer the possibility to use t hem in the future applications.展开更多
石墨烯具有优异的光电性能,是极具潜力的新一代导电材料。采用传统的热化学气相沉积法制备单层石墨烯需要高温反应条件,试验尝试采用等离子体增强化学气相沉积法(Plasma Enhanced Chemical Vapor Deposition,PECVD),在550℃的反应温度下...石墨烯具有优异的光电性能,是极具潜力的新一代导电材料。采用传统的热化学气相沉积法制备单层石墨烯需要高温反应条件,试验尝试采用等离子体增强化学气相沉积法(Plasma Enhanced Chemical Vapor Deposition,PECVD),在550℃的反应温度下,较短的反应时间内,在铜箔衬底上制备出石墨烯薄膜。考察了甲烷和氢气流量比、氩气的作用以及衬底通电与否等因素对石墨烯生长的影响。研究发现,在甲烷与氢气流量比为1∶1,通入氩气,不给铜箔衬底通电的试验条件下,制备出的石墨烯薄膜电阻值为4.15 kΩ,显示出较好的光电特性。展开更多
The synthesis of carbon nanotubes￡¨CNTs ￡(c)at low temperature has received a gre at deal of attention and be-comes a challenging issue￡(r)But few mo del which accounts for the growth of C NTs is suited for th...The synthesis of carbon nanotubes￡¨CNTs ￡(c)at low temperature has received a gre at deal of attention and be-comes a challenging issue￡(r)But few mo del which accounts for the growth of C NTs is suited for the synthesis of CNTs by microwave plasma chemical vapor deposition￡¨MWPCVD￡(c)at low temperature because most rese archers conclude that the growth mechanism is determi ned by the catalyst-supporter interaction while ignored the diffusion o f carbon in the catalyst￡(r)In this paper,under the catalytic effect of cobalt supported by SiO 2 and Al 2 O 3 ,CNTs are synthe-sized by MWPCVD at about 500℃,and tip-growth,the model which accounts fo r the catalytic growth of CNTs is outlined￡(r)It is the temperature difference between the upper and bottom o f the catalytic particle that results in the diffusion of carbon atoms from upper to the bottom,and precipitation of s aturated carbon on the bottom surface to form CNTs￡(r)展开更多
In this paper, under the catalytic effect of nickel particles electro-deposited on Ni substrate, self-aligned carbon nanotubes were synthesized by microwave plasma chemical vapor deposition with a mixture of methane a...In this paper, under the catalytic effect of nickel particles electro-deposited on Ni substrate, self-aligned carbon nanotubes were synthesized by microwave plasma chemical vapor deposition with a mixture of methane and hydrogen gases at 510 ℃. During the process of nanotubes growth, the total pressure in the chamber was kept at 3 kPa, the microwave plasma input power was 500 W, and the flow rates of H 2 and CH 4 were 50 and 1 mL/min, respectively. The aligned features and hollow structure have been verified by scanning electron and transmission electron microscopic images. As the nanotubes grow, the nickel cap remains on the tip of the carbon nanotubes. The nanotubes′diameter is about 70 nm and they have bamboo structures. Because of the strong etching ability of hydrogen plasma and the low volume ratio of H 2/CH 4, no carbonaceous particles attached to the carbon nanotubes were found. It demonstrats that MWPCVD is a very efficient process for the synthesis of the aligned carbon nanotubes at a low temperature. The aligned CNTs grown on Ni substrate at such a low temperature are suitable for device fabrication.展开更多
文摘Well aligned nanotubes with diameter of 30—50 nm have been synthesized on a porous alumina template by microwave plasma enhanced chemical vapor deposition (MW PECVD). By this means, the control over either diameter or length of the nanotubes could be realized. The hollow structure and vertically aligned features have been verified by scanning electron and transmission electron microscopic images. In comparison with the reported fabrication methods, lower synthesis temperature (below 520 ℃) and simpler process (no negative dc bias applied) have been achieved, which could be of great importance for both theoretical research and pratical applications.
文摘Among the three main methods for the s ynthesis of carbon nanotubes(CNTs ),chemical vapor deposition(CVD)has received a great deal of attentio n since CNTs can be synthesized at sig nificantly low temperature.Plasma chemical vapor deposition me thods can synthesize CNTs at lower te mperature than thermal CVD.But in th e usual catalytic growth of CNTs by CVD,CNTs are often tangled together and have some defects.These will limit t he property research and potential applications.How to synthesize the str aight CNTs at low temperature become s a challenging issue.In this letter,s traight carbon nanotube(CNT)films were achieved by microwave pla sma chemical vapor deposition(MWPCVD)catalyzed by round Fe-Co-Ni alloy particles on Ni substrate at 610℃.It wa s found that,in our experimental condition,the uniform growth rate along the circumference of round alloy particles plays a very important role in the gro wth of straight CNT films.And because the substrate is conducting,the straight CNT films grown at low temperature ma y have the benefit for property research and offer the possibility to use t hem in the future applications.
基金Supported by Hunan Province Nature Science Foundation of China(No.03JJY3015)and Foundation for University Key Teacher by the Ministry of Education(2000-06)
文摘The synthesis of carbon nanotubes￡¨CNTs ￡(c)at low temperature has received a gre at deal of attention and be-comes a challenging issue￡(r)But few mo del which accounts for the growth of C NTs is suited for the synthesis of CNTs by microwave plasma chemical vapor deposition￡¨MWPCVD￡(c)at low temperature because most rese archers conclude that the growth mechanism is determi ned by the catalyst-supporter interaction while ignored the diffusion o f carbon in the catalyst￡(r)In this paper,under the catalytic effect of cobalt supported by SiO 2 and Al 2 O 3 ,CNTs are synthe-sized by MWPCVD at about 500℃,and tip-growth,the model which accounts fo r the catalytic growth of CNTs is outlined￡(r)It is the temperature difference between the upper and bottom o f the catalytic particle that results in the diffusion of carbon atoms from upper to the bottom,and precipitation of s aturated carbon on the bottom surface to form CNTs￡(r)
文摘In this paper, under the catalytic effect of nickel particles electro-deposited on Ni substrate, self-aligned carbon nanotubes were synthesized by microwave plasma chemical vapor deposition with a mixture of methane and hydrogen gases at 510 ℃. During the process of nanotubes growth, the total pressure in the chamber was kept at 3 kPa, the microwave plasma input power was 500 W, and the flow rates of H 2 and CH 4 were 50 and 1 mL/min, respectively. The aligned features and hollow structure have been verified by scanning electron and transmission electron microscopic images. As the nanotubes grow, the nickel cap remains on the tip of the carbon nanotubes. The nanotubes′diameter is about 70 nm and they have bamboo structures. Because of the strong etching ability of hydrogen plasma and the low volume ratio of H 2/CH 4, no carbonaceous particles attached to the carbon nanotubes were found. It demonstrats that MWPCVD is a very efficient process for the synthesis of the aligned carbon nanotubes at a low temperature. The aligned CNTs grown on Ni substrate at such a low temperature are suitable for device fabrication.
