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用巨正则蒙特卡罗分子模拟方法研究了单壁纳米碳管中的微孔即单壁纳米碳管基本孔-内管腔和管间孔对单壁纳米碳管储氢性能的影响.与低温下氮气吸附实验结果的比较发现单壁纳米碳管的内管腔是吸附的主要位置.分析单壁纳米碳管内管腔中吸附势的叠加和利用效率,发现管径为2nm左右时单壁纳米碳管内管腔的储氢容量最高.当单壁纳米碳管阵列的管间距增加时,单壁纳米碳管的管间孔也会成为有效的氢吸附位.
关键词:
Monte Carlo方法
单壁纳米碳管
储氢
微孔 相似文献
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超细0.4nm直径单壁碳管的光学特性 总被引:1,自引:1,他引:0
由于纳米碳管的优异机械特性及其丰富多采的光学和电学特性,它自1991年被发现以来一直受到科学家的青睐,纳米碳管研究已成为当今世界上发展最迅速,竞争最激烈的科学前沿领域之一。怎样才能把纳米碳管做得更细小,尺寸更均匀以及如何使众多的纳米碳管排列规整,一直是纳米碳管研究中的难题。我们利用多孔的沸石晶体作为载体,首次成功地研制出了尺寸均一,排列规整的超细单壁纳米碳管,这些超细纳米碳管具有独特的性能,低温下(<20K)甚至呈现出前所未有的一维超导现象。详细介绍了这些超细单壁纳米碳管的制备过程,并着重介绍其在可见光区的光吸收,光发射以及二次谱波的倍频特性。 相似文献
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利用双水电极介质阻挡放电装置,采用光谱方法测量了大气压氩气介质阻挡放电微放电通道 中的电子温度的时间演化.选取波长为69654nm(2P2→1S5),763 51nm(2P6→1S5 ),77242nm(2P2→1S3)的氩原子谱线进行了时间分辨测量.实验 发现在放电期间,电 压波形开始下降,在放电熄灭后又开始上升.高能级为2P2的跃迁(77242nm和 69654nm )比2P6的跃迁76351nm要延迟几十ns.根据其时间分辨谱,估算了微放电中的 电子激发 温度的时间演化,结果表明,电子激发温度并不是一个恒定值,而是随时间变化的.当放电 电流达到最大值,即电子密度达到最大值时,其电子温度并未达到最大值,而经过200ns 后 才达到最大值.
关键词:
大气压介质阻挡放电
发射光谱
电子激发温度
微放电通道 相似文献
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运用分子动力学方法具体模拟研究单个碳纳米管(CNTs)在加热过程中的结构变化.选择多组不同结构的单壁碳纳米管(SWCNTs)和双壁碳纳米管(DWCNTs)作为研究对象,加热温度从室温开始到4000 K,压强保持为1 atm.结果表明单壁碳管中手性型结构热稳定性最好,其次是扶手椅型和锯齿型,当手性角相同时,直径大的热稳定性更高;对于双壁碳管,研究表明当双壁中至少之一为手性结构时其热稳定好,而内外壁均为锯齿结构的稳定性最差,该结果进一步支持了有关单壁碳管的结论;还从理论上探索了描述结构热稳定性的方式,并在键层
关键词:
单壁碳纳米管
双壁碳纳米管
分子动力学方法
热稳定性能 相似文献
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以Y/Ni为催化剂制备的单壁碳纳米管的拉曼光谱研究 总被引:1,自引:0,他引:1
采用电弧放电法以Y/Ni为催化制备了单壁碳纳米管(SWNTs),对样品进行了扫描电镜、透射电镜和拉曼光谱的研究。所制备的样品中单壁碳纳米管的含量较高。对单壁碳纳米管的共振拉曼散射增强效应进行了观察,随激光波长的不同,单壁碳纳米管的拉曼光谱也随之变化,尤其是低频区径向呼吸模的变化比较明显。利用布里渊区折叠法计算了单壁碳纳米管的电子态密度曲线,根据SWNTs电子态密度尖峰之间的能量差、管子的直径和呼吸模频率建立了一个图表,并对SWNTs的呼吸模进行了归属。分析结果表明:样品中单壁碳纳米管的直径分布在0.79-1.76nm范围,金属管和半导体管均存在,并且直径在1.45nm附近的碳管居多。 相似文献
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Synthesis of single-wall carbon nanotubes (SWNTs) was carried out by an ablation method using a XeCl excimer laser. It was irradiated onto a graphite target containing Co and Ni at the temperatures of 1073, 1173, 1273, 1373, 1473, 1523 and 1623 K under the atmosphere (0.1 MPa) of Ar gas with the flow rate of 12 ml/min. The measurement by a scanning/transmission electron microscope and Raman spectroscopy found the formation of SWNTs with the diameter of about 1.3 nm and the length of about 2 μm in ablated carbonaceous soot. The ratio of peak intensity of 1590 cm−1 (G band) to that of 1335 cm−1 (D band) in the high frequency Raman spectra increased with increasing the ambient temperature. The radial breathing mode (RBM) in the low frequency Raman spectra shows that the mean diameter of SWNTs increased with increasing the ambient temperature. 相似文献
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V. N. Bezmel’nitsyn A. G. Domantovskii A. V. Eletskii E. V. Obraztsova A. G. Pernbaum K. E. Prikhod’ko S. V. Terekhov 《Physics of the Solid State》2002,44(4):656-658
The high-yield synthesis of single-walled carbon nanotubes (SWNTs) is carried out in an electric-arc discharge using the Ni-Cr alloy as a catalyst. A new method of introducing the catalyst into the plasma hot region is used in the synthesis. In this method, the anode with a sandwich structure consists of two longitudinal graphite rods of a rectangular cross section, between which the Ni-Cr alloy in the form of a foil having a thickness approximately equal to 0.2 mm is placed. The obtained samples are investigated using transmission electron microscopy (TEM), Raman spectroscopy, and thermogravimetry. According to the results of TEM observations, SWNTs are tied into bundles with a length of several micrometers and a diameter of about 10 nm. The Raman spectra indicate that the diameter distribution of SWNTs lies between 1.2 and 1.5 nm with a peak at approximately 1.24 nm. The SWNT content in the obtained samples is approximately 20%. Heat treatment at various temperatures with a dosed air supply leads to a noticeable mass loss of the sample and to a change in its composition. For example, thus heating to 600 K causes a mass loss of about 40%, leading to an increase in the content of SWNTs up to 35% without their noticeable destruction. Further heating above 600 K leads to a virtually complete thermal decomposition of SWNTs. 相似文献
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S. Suzuki T. Mizusawa T. Okazaki Y. Achiba 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,52(1-3):83-86
Single-walled carbon nanotubes made by using arc-burning technique in nitrogen atmosphere were dispersed in sodium cholate (SC) solution, and the diameter and chirality distribution of semiconductive SWNTs was investigated by UV-VIS-NIR and Raman spectroscopy, and photoluminescence mapping technique. In the typical formation condition, the diameter distribution of them is found to be relatively narrow (1.2 nm–1.4 nm in diameter), less chirality dependent, almost the same as the diameter distribution of SWNTs obtained by using laser-furnace technique. 相似文献
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M.V. Chernysheva A.A. Eliseev A.V. Lukashin Yu.D. Tretyakov S.V. Savilov N.A. Kiselev O.M. Zhigalina A.S. Kumskov A.V. Krestinin J.L. Hutchison 《Physica E: Low-dimensional Systems and Nanostructures》2007,37(1-2):62
The present study is focused on the synthesis and investigation of the nanocomposite CuI@SWNT obtained by the filling of metallic single-walled carbon nanotubes (SWNTs) (inner diameter 1–1.4 nm) by wide-gap semiconducting CuI nanocrystals using so-called capillary technique. The method is based on the impregnation of pre-opened SWNTs by molten CuI in vacuum with subsequent slow cooling to room temperature. SWNTs and CuI@SWNT nanocomposites were studied by nitrogen capillary adsorption method, EDX microanalysis, HRTEM microscopy and Raman spectroscopy. The changing of electronic properties of CuI@SWNT as compare to row nanotubes was observed. 相似文献
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We demonstrate that zinc oxide can catalyze the growth of single-walled carbon nanotubes (SWNTs) with high efficiency by a chemical vapor deposition process. The zinc oxide nanocatalysts, prepared using a diblock copolymer templating method and characterized by atomic force microscopy (AFM), were uniformly spaced over a large deposition area with an average diameter of 1.7 nm and narrow size distribution. Dense and uniform SWNTs films with high quality were obtained by using a zinc oxide catalyst, as characterized by scanning electron microscopy (SEM), Raman spectroscopy, AFM, and high-resolution transmission electron microscopy (HRTEM). 相似文献
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S. Suzuki N. Asai H. Kataura Y. Achiba 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,43(1-3):143-146
The formation of single-wall carbon nanotubes (SWNTs) by using laser vaporization technique in different ambient gas atmosphere
was investigated. SWNTs were prepared with Rh/Pd (1.2/1.2 atom%)-carbon composite rod in Ar and nitrogen gas atmosphere, respectively.
Raman spectra of raw carbon materials including SWNTs and photoluminescence mapping of dispersed SWNTs in a surfactant solution
demonstrate that the diameter distribution of SWNTs prepared in Ar atmosphere is narrower than those obtained by using CVD
technique (e.g. HiPco nanotube), even when the ambient temperature is as high as 1150 ○C. It was also found that nitrogen atmosphere gives wider diameter distribution of SWNTs than that obtained with Ar atmosphere.
Furthermore, the relative yield of fullerenes (obtained as byproducts) is investigated by using HPLC (high-performance liquid
chromatography) technique. It was found that the relative yield of higher fullerenes becomes lower, when nitrogen is used
as an ambient gas atmosphere. Based on these experimental findings, a plausible formation mechanism of SWNTs is discussed. 相似文献
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S. Suzuki R. Sen T. Tamaki H. Kataura Y. Achiba 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,24(1-3):401-404
Single-walled carbon nanotubes (SWNTs) were prepared with
double laser vaporization of a graphite target and a metal/alloy
target inside an electric furnace at 1200
°C ambient temperature with 500 torr
Ar gas atmosphere. Each target was vaporized simultaneously with
a different Nd:YAG laser. Several kinds of metal/alloy target
(Ni, Co, Fe, and permalloy) were tested in order to see the
difference in the resulting SWNT yield and the diameter
distribution of them. The Raman spectra of SWNT-containing soot
prepared by use of this technique with permalloy/carbon system
indicated that permalloy gives almost the same yield as compared
with Ni/Co carbon composite rod with single laser vaporization
technique, though the diameter distribution of them is slightly
different. Also, time-resolved images of the plume by carbon and
permalloy nanoparticles after laser vaporization were collected
using a high-speed video camera. These images suggest that the
hot plumes due to carbon and permalloy nanoparticles do not mix
together so extensively, at least in a few hundred microseconds
after laser vaporization. The effect of time delay between two
laser pulses on the yield and the diameter distribution of SWNTs
was also presented and discussed. 相似文献
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A detailed Raman study on thin single-wall carbon nanotubes prepared by the HiPCO process 总被引:2,自引:0,他引:2
A. Kukovecz Ch. Kramberger V. Georgakilas M. Prato H. Kuzmany 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,28(2):223-230
The Raman spectrum of single wall carbon nanotubes (SWNTs) prepared by high pressure CO decomposition (HiPCO process) has
been recorded at nine excitation laser energies ranging from 1.83 eV to 2.71 eV. The characteristic nanotubes features: G
band, D band and radial breathing mode (RBM) have been analyzed and compared to those of an arc discharge SWNT material of
similar diameter. A strong Breit-Wigner-Fano type (metallic) contribution to the G band was found in the spectra measured
with green lasers, while spectra measured with red lasers indicate resonances of semiconducting SWNTs. Analysis of the energy
dependence of the position of the D band revealed sinusoid oscillations superimposed on a linear trend. The validity of full
DOS calculations for HiPCO materials has been confirmed by a match found between the estimated spectral contribution of metallic
SWNTs as calculated from the components of the measured G band and as predicted by the (n, m) indexes of the major scatterers of DOS simulations. The RBM region of the HiPCO spectrum is more complex than usually observed
for SWNTs. The analysis performed with a Gaussian distribution and improved fitting parameters leads to a mean diameter and
variance of 1.05 nm and 0.15 nm, respectively. A bimodal Gaussian distribution had little influence on the error sum but reduced
the standard error slightly. The major spectral features of the RBM could be interpreted using available resonance Raman theory.
Received 5 February 2002 / Received in final form 3 April 2002 Published online 19 July 2002 相似文献