共查询到18条相似文献,搜索用时 140 毫秒
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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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采用经典分子动力学方法研究了压力驱动作用下水在石墨烯碳纳米管复合结构中的渗透特性.研究结果表明,水分子渗透通过石墨烯碳纳米管复合结构的渗透率明显高于石墨烯碳纳米管组合结构.水在石墨烯碳纳米管复合结构中的渗透率随着压强的升高而增大,随着电场强度的增大而减小.考虑了温度和复合结构中双碳管轴心距对水渗透性的影响规律.系统温度越高,水的渗透率越高;随着双碳管轴心距的增加,水的渗透率逐渐降低.通过计算分析水流沿渗透方向的能障分布,解释了各参数变化对水在石墨烯碳管复合结构中渗透特性的影响机理.研究结果将为基于石墨烯碳管复合结构的新型纳米水泵设计提供一定的理论依据. 相似文献
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爆发沸腾换热和纳米流体传热具有很重要的理论和实用意义.但由于爆发沸腾传热过程中,液体内部空间温度梯度大,相变速度快,表现出一定的特殊性,纳米流体传热对其传热过程机理的研究,往往需要在实验条件难以实现的空间和时间极限下,充分研究液相和气相内部的温度、压力和运动状态及其空间分布.采用分子动力学的方法,通过对比研究纯水和碳纳米管/水混合体系爆发沸腾过程,对两种体系密度分布、温度场和应力场研究和对比分析,揭示碳纳米管/水混合体系的强化换热机理,探究碳纳米管对混合体系爆发沸腾换热和纳米流体传热的促进作用. 相似文献
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图1所示是探究液体压强规律的演示器材,用于演示:
(1)液体内部向各个方向都有压强;
(2)同一深度液体向各个方向的压强相等;
(3)液体压强随深度的增加而增大.
但在使用过程中,由于玻璃筒各端口都用橡皮膜封住,无法与外界大气压相通.当将实验器材置于水槽中时,玻璃筒内的密闭气体由于橡皮膜向内凹陷而被压缩,导致内部气体压强增大,影响橡皮膜向内凹陷的程度,从而影响了实验的直观效果. 相似文献
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我们教研组举行了一次观摩教学,这一堂课所讲的内容,是初中物理学第三章液体和气体中§35大气压,§36抽水机,§37大气压的值(参看初中物理上册§35、§36、§37)。这三节是在同学们对液体压强的一些性质有了一般的了解和知道了气体也有重量的基础上进行的,主要是要让同学们了解:有大气压存在,大气压应用的实例——抽水机的构造原理及大气压的值。为了使新课与旧课很好地联系起来,我在复习、提问时,向同学们提出了这样的问题,物体在液体内部是否受到了液体的压力?找一个同学回答,当他作了肯定的回答之后,接着问他,这压力是怎样产生的呢?其压强是按什么公式计算的呢?当他回答好这些问题之后,就在总结复习提问的基础上很自然的引人了新课。既然由 相似文献
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《Current Applied Physics》2008,8(2):217-221
In this paper, transport of liquid mercury under pressure through double-walled carbon nanotubes is studied using classical molecular dynamics simulations in conjunction with a pressure control model. The results indicate that wetting of double-walled carbon nanotubes by mercury occurs above a threshold pressure of liquid mercury. Liquid mercury can be transported through the inner tube of double-walled carbon nanotubes with the continuous increase of its pressure. The threshold pressure of liquid mercury decreases and the transport efficiency increases greatly with enlarging the inner tube size. The space between the two walls of double-walled carbon nanotubes can also transport the liquid mercury while the distance between the two walls is much larger than the radius of the inner tube. Transport efficiency of double-walled carbon nanotubes is a little lower than that of single-walled carbon nanotubes while double-walled carbon nanotubes transport liquid more steadily than single-walled carbon nanotubes. 相似文献
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《Current Applied Physics》2009,9(4):750-754
On the basis of the atomistic simulations of electrowetting in single-walled carbon nanotubes, electrowetting of double-walled carbon nanotubes by mercury is studied using classical molecular dynamics simulations. Wetting of double-walled carbon nanotubes by mercury occurs above a threshold size of inner tube when the voltage is applied on the outer tube, but no wetting phenomenon appears when the voltage is applied on the inner tube. The filling rate increases greatly with enlarging the inner tube size. The space between the two walls of double-walled carbon nanotubes cannot be filled by mercury during electrowetting process. 相似文献
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单壁碳纳米管在高压下会发生结构相变,导致金属型的碳纳米管变成半导体.相变后碳纳米管中电子的库仑关联的表现形式发生变化,从Luttinger liquid行为转变成环境量子涨落行为.同时,相变后电子波函数的相位关联导致弱局域化行为的出现.为了研究库仑关联和相位关联之间是否有相互影响,使用金刚石对顶砧和液压自锁高压包在0—10 GPa准静压范围内测量了单层碳纳米管样品在低温和不同磁场下的微分电导随偏压的依赖关系.实验结果表明,相位关联和库仑关联是两种独立的效应,各自影响着电子的输运行为.
关键词:
单层碳纳米管
高压
微分电导 相似文献
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P. N. Gevko A. V. Okotrub L. G. Bulusheva I. V. Yushina U. Dettlaff-Weglikowska 《Physics of the Solid State》2006,48(5):1007-1011
The thermal stability of initial and purified samples of single-walled carbon nanotubes prepared through gas-phase disproportionation of carbon monoxide CO in the presence of iron particles under high pressure (the HiPCO method) is investigated using optical absorption spectroscopy and thermogravimetry. An analysis of the optical absorption spectra demonstrates that thermal oxidation of the initial material proceeds rather rapidly and uniformly owing to the catalytic effect caused by the presence of iron particles in the sample. The destruction of the carbon nanotubes contained in the as-prepared and purified samples begins at temperatures of ~250 and ~300°C, respectively. It is shown that single-walled metallic nanotubes undergo faster oxidation as compared to the single-walled semiconducting nanotubes. 相似文献
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J. Nygard D.H. Cobden M. Bockrath P.L. McEuen P.E. Lindelof 《Applied Physics A: Materials Science & Processing》1999,69(3):297-304
We review transport measurements on single-walled carbon nanotubes contacted by metal electrodes. At room temperature some
devices show transistor action similar to that of p-channel field effect transistors, while others behave as gate-voltage
independent wires. At low temperatures transport is usually dominated by Coulomb blockade. In this regime the quantum eigenstates
of the finite-length tubes can be studied. At higher temperatures power law behaviour is observed for the temperature and
bias dependence of the conductance. This is consistent with tunneling into a one-dimensional Luttinger liquid in a nanotube.
We also discuss recent developments in contacting nanotubes which should soon allow study of their intrinsic transport properties.
Received: 17 May 1999 / Accepted 18 May 1999 / Published online: 4 August 1999 相似文献
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运用第一性原理的密度泛函理论,结合非平衡格林函数,研究了氮原子取代掺杂手性单壁(6,3)碳纳米管的电子结构和输运特性.计算结果表明:不同构形和不同数目的氮原子取代掺杂对手性碳管的输运性质有很复杂的影响.研究发现,氮原子掺杂明显改变了碳管的电子结构,使金属型手性碳管的输运性能降低,电流-电压曲线呈非线性变化,而且输运性能随着杂质原子间间距的变化而发生显著改变.在一定条件下,金属型碳管向半导体型转变.
关键词:
手性单壁碳纳米管
氮掺杂
电子结构
输运性能 相似文献
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Cristina Bena Smitha Vishveshwara Leon Balents Matthew P. A. Fisher 《Journal of statistical physics》2001,103(3-4):429-440
The Luttinger model of the one-dimensional Fermi gas is the cornerstone of modern understanding of interacting electrons in one dimension. In fact, the enormous class of systems whose universal behavior is adiabatically connected to it are now deemed Luttinger liquids. Recently, it has been shown that metallic single-walled carbon nanotubes are almost perfectly described by the Luttinger Hamiltonian. Indeed, strongly non-Fermi liquid behavior has been observed in a variety of DC transport experiments, in very good agreement with theoretical predictions. Here, we describe how fractional quasiparticle charge, a fundamental property of Luttinger liquids, can be observed in impurity-induced shot noise. 相似文献