在镍基板上低温生长纳米碳管膜

纳米碳管在储能材料和场发射材料等方面具有非常广阔的应用前景。在纳米碳管的许多潜在用途中要求纳米碳管直接低温生长在具有导电能力的基板材料上。以镍片为基板材料,利用微波等离子体化学气相沉积法在低温条件下合成了纳米碳管膜。研究表明,高纯度纳米碳管的低温合成取决于氢等离子体对碳源的有效裂解以及在纳米碳管形成初期对碳素物质的刻蚀。同时,随着微波功率的上升,纳米碳管的纯度上升、生长速率加快且形状变得较直。     

单壁纳米碳管制备方法的新进展

纳米碳管以其独特的结构、优异的物理化学性质以及超高的力学性能而具有巨大的应用前景．单壁纳米碳管作为纳米碳管结构的基础，在纳米电子器件、单电子器件、储能材料等方面表现出了良好的性能．基于对单壁纳米碳管的研究，综述了近年来在单壁纳米碳管制备技术方面取得的最新进展，其中包括电弧放电法、化学气相沉积法以及激光蒸发法等方法，并讨论了在不同方法中影响单壁纳米碳管生长的几个关键因素．     

一种基于CVD法的纳米碳管微观分析及场致发射特性的研究

将化学气相沉积法（CVD）制备的纳米碳管提纯后，用透射电镜（TEM）观测了它的微观结构，通过实验对纳米碳管在不同温度下生长的结构特性进行了分析比较，得出了纳米碳管生长的最佳温度为750℃；并对纳米碳管粉体的拉曼（Raman）光谱进行了分析，得到了与透射电镜观测相一致的结论；最后测试了纳米碳管的场致发射特性．     

中国纳米功能材料研究取得重大成果

中国科学家在纳米管和其他功能纳米材料研究方面取得了７项具有重要影响的成果。这７项重要成果是：（１）大面积定向碳管阵列合成。研究人员发展了利用化学气相法高效制备纯净碳纳米管技术,用这种创新技术合成的纳米管,孔径基本一致,约２０纳米,长度约１００微米,纳米管阵列面积达到３毫米×３毫米。其定向排列程度高,碳纳米管之间间距为１００微米。这种大面积定向纳米碳管阵列,在平板显示的场发射阴极等方面有重要应用前景。（２）超长纳米碳管制备。研究人员利用改进后的基底,成功地控制了碳纳米管的生长模式,实现了催化剂颗料…     

由不同碳源合成及制备纳米碳管的进展

纳米碳管可通过石墨、煤炭及炭黑等高含碳固体物，甲烷、乙烯或苯之类的有机化合物，一氧化碳和碳化硅等含碳无机化合物的转化来制备，甚至还可由低分子芳烃化合物来逐级合成。根据各种不同碳源，按不同转化过程及制备方法进行了总结与归纳，期望能对纳米碳管的合成及制备有一总体理解；通过简要、系统地介绍各种转化过程及制备方法，并对其中一些有发展前途的方法特别是电弧法、激光烧蚀法及化学气相沉积法的最新改进和发展进行了考察，分析了这些方法的优缺点；最后概述了目前纳米碳管规模制备方法的进展情况。     

合成碳包覆纳米金属材料的研究现状

合成碳包覆纳米金属材料具有奇特的电学、光学和磁学性质,是纳米科技方面一个非常活跃且众人关注的课题.总结了合成碳包覆纳米金属材料具有代表性的方法,如电孤放电法、化学气相沉积法、高温热解法、低温热解法、聚能法、爆轰法等.简要综述了其合成机理及优缺点.     

定向生长碳纳米管阵列的制备及其应用研究进展

碳纳米管在力、热、光、电等方面都显示出独特的性质，受到众多领域专家的广泛关注，而定向生长的碳纳米管阵列的获得具有更深远的科学意义。详细介绍了国内外定向生长碳纳米管阵列的制备方法，重点阐述了化学气相沉积法（CVD）的制备流程和生长机理以及其工艺参数对生成碳管阵列的影响。简要论述了碳纳米管阵列在几个典型应用领域的研究进展。     

化学气相沉积法快速生长定向纳米碳管

利用化学气相沉积法，采用二甲苯为碳源，二茂铁为催化剂，氮气作保护气，在石英基底上催化裂解生长定向纳米碳管，试验结果表明：在775℃，120min的条件下，可生长出长达200μm厚的定向纳米碳管薄膜；在775℃，反应时间为60min～120min时，纳米碳管的长度为100μm～200μm，而纳米碳管的直径变化不明显。而无氢气，较高的反应温度和连续的催化剂供给对快速生长定向纳米碳管有重要的影响。     

高质量小直径单壁纳米碳管的CVD法制备

使用溶胶凝胶法制备了Fe/Mo/MgO催化剂,用化学气相沉积法在1000℃下催化裂解甲烷,制备了高质量的单壁纳米碳管.用SEM、TEM、HRTEM、TGA和Raman等方法对制备的纳米碳管粗产品进行了表征.结果表明:该产物确为单壁纳米碳管,单壁纳米碳管直径十分均一,在0.86～0.90nm之间,且其形态基本上都是以束状存在;本方法所制得粗产物中单壁碳管的含量在30%以上.     

纳米铜导电油墨的制备及其应用

综述了纳米铜粒子的制备方法,即机械球磨法、辐射合成法、物理气相沉积法等物理制备法及化学制备法,探讨了改进纳米铜导电油墨防氧化、低温烧结、导电性能等关键问题,以及纳米铜导电油墨在印刷RFID电子标签、薄膜开关、触摸屏等方面的应用,并提出纳米铜导电油墨未来的研究方向为：抗氧化、低温烧结、多种印刷方式及产品应用等研究。     

Carbon nanotube thermal interface material for high-brightness light-emitting-diode cooling

Aligned carbon nanotube (CNT) arrays were fabricated from a multilayer catalyst configuration by microwave plasma-enhanced chemical vapor deposition (PECVD). The effects of the thickness and annealing of the aluminum layer on the CNT synthesis and thermal performance were investigated. An experimental study of thermal resistance across the CNT array interface using the modified ASTM D5470 standard was conducted. It was demonstrated that the CNT-thermal interface material (CNT-TIM) reduced the thermal interfacial resistance significantly compared with the state-of-art commercial TIM. The optimized thermal resistance of the CNT arrays is as low as 7?mm(2)?K?W(-1). The light performance of high-brightness light-emitting diode (HB-LED) packages using the aligned CNT-TIM was tested. The results indicated that the light output power was greatly improved with the use of the CNT-TIM. The usage of the CNT-TIM can be also extended to other microelectronics thermal management applications.     

Growth of ultra long multiwall carbon nanotube arrays by aerosol-assisted chemical vapor deposition

Using a home-made aerosol nebulizer, we developed a new aerosol-assisted chemical vapor deposition (AACVD) process that made it possible to synthesize vertically-aligned carbon nanotube (VACNT) arrays with heights over a few millimeters routinely. An essential part of this technique was in-situ formation of metal catalyst nanoparticles via pyrolysis of ferrocene-ethanol aerosol right before CNT synthesis. Through the optimization of aerosol supply and CVD process parameters, we were able to synthesize clean VACNT arrays as long as 4.38 mm with very low metal contents in 20 min. Furthermore, it is worthy noting that such an outstanding height is achieved very quickly without supporting materials and water-assistance. By taking advantage of almost complete inhibition of CNT growth on low melting-temperature metals, we were able to fabricate patterned VACNT arrays by combining AACVD process with a conventional photolithograpic patterning of gold lines. Characterizations of as-grown nanotubes such as morphology, purity, and metal contents are presented.     

CVD growth of carbon nanotubes on thin-film Ni20Ti35N45 alloy catalyst

The possibility of forming carbon nanotube (CNT) arrays on a Ni–Ti–N catalytic alloy with low nickel content by chemical vapor deposition (CVD) is demonstrated. Adding nitrogen to the Ni–Ti alloy composition favors the formation of TiN compound and segregation of Ni on the surface, where it produces a catalytic effect on the CNT growth. It is found that, using CVD from acetylene gas phase at a substrate temperature of 650°C, a CNT array of 9-µm height can be grown for 2 min.     

Effect of density variation and non-covalent functionalization on the compressive behavior of carbon nanotube arrays

Arrays of aligned carbon nanotubes (CNTs) have been proposed for different applications, including electrochemical energy storage and shock-absorbing materials. Understanding their mechanical response, in relation to their structural characteristics, is important for tailoring the synthesis method to the different operational conditions of the material. In this paper, we grow vertically aligned CNT arrays using a thermal chemical vapor deposition system, and we study the effects of precursor flow on the structural and mechanical properties of the CNT arrays. We show that the CNT growth process is inhomogeneous along the direction of the precursor flow, resulting in varying bulk density at different points on the growth substrate. We also study the effects of non-covalent functionalization of the CNTs after growth, using surfactant and nanoparticles, to vary the effective bulk density and structural arrangement of the arrays. We find that the stiffness and peak stress of the materials increase approximately linearly with increasing bulk density.     

碳纳米管阵列研究进展

在介绍CNT阵列性能的基础上,对国内外直接合成CNT阵列的方法进行了评述,重点阐述了各种方法的基本特点及CNT阵列的生长机理、结构控制和批量制备问题。进而探讨了CNT原生阵列、抽丝形成的CNT丝、以及CNT阵列分散后得到的CNTs在复合材料、力学增强、功能器件等方面的初步应用,展望了CNT阵列的发展趋势,指出低成本、大批量可控制备CNT阵列仍然是未来一段时间内国际研究热点。     

Ultra‐High Optical Absorption Efficiency from the Ultraviolet to the Infrared Using Multi‐Walled Carbon Nanotube Ensembles

The optical absorption efficiencies of vertically aligned multi‐walled (MW)‐carbon nanotube (CNT) ensembles are characterized in the 350?7000 nm wavelength range where CNT site densities > 1 × 10¹¹/cm² are achieved directly on metallic substrates. The site density directly impacts the optical absorption characteristics, and while high‐density arrays of CNTs on electrically insulating and non‐metallic substrates have been commonly reported, achieving high site‐densities on metals has been challenging and remains an area of active research. These absorber ensembles are ultra‐thin (<10 μm) and yet they still exhibit a reflectance as low as ～0.02%, which is 100 times lower than the reference; these characteristics make them potentially attractive for high‐sensitivity and high‐speed thermal detectors. In addition, the use of a plasma‐enhanced chemical vapor deposition process for the synthesis of the absorbers increases the portfolio of materials that can be integrated with such absorbers due to the potential for reduced synthesis temperatures. The remarkable ruggedness of the absorbers is also demonstrated as they are exposed to high temperatures in an oxidizing ambient environment, making them well‐suited for extreme thermal environments encountered in the field, potentially for solar cell applications. Finally, a phenomenological model enables the determinatiom of the extinction coefficients in these nanostructures and the results compare well with experiment.     

Height independent compressive modulus of vertically aligned carbon nanotube arrays

The compressive modulus of dense vertically aligned multiwalled carbon nanotube (CNT) arrays synthesized by chemical vapor deposition was investigated using an optically probed precision-loading platform. For CNT arrays with heights ranging from 15 to 500 microm, the moduli were measured to be about 0.25 MPa and were found to be independent of array height. A continuum mechanics model based on multimode buckling guided by the wavy features of CNT arrays is derived and explains well the measured compressive properties. The measured compressive modulus of the CNT arrays also satisfies the "Dahlquist tack criterion" for pressure sensitive adhesives, which was previously observed for these vertically aligned CNT arrays (Zhao, Y., et al. J. Vac. Sci. Technol., B 2006, 24, 331-335).     

Nitrogen-doped carbon nanotube arrays grown on graphene substrate

Nitrogen-doped carbon nanotube (N-doped CNT) arrays have been synthesized on graphene substrate by chemical vapor deposition process, in which iron nanoparticles (NPs) assembled on the graphene sheet were generated in situ from the reduction of Fe₃O₄ NPs/reduced graphene oxide (RGO) and were used as catalyst. The morphology and structure of the N-doped CNT arrays were investigated by field emission scanning electron microscope and high-resolution transmission electron microscope. The N-doped CNTs were bamboo-shaped and the density can be controlled by modulating the density of catalyst NPs on RGO sheets. The concentration and incorporation of nitrogen were studied by elemental analysis, X-ray photoelectron spectroscope and Raman analysis, and the results showed that the nitrogen content was around 3 wt.%. Because of the good conductivity of graphene structure, N-doped CNT arrays grown on graphene substrate may be promising candidates as noble metal-free electrodes for oxygen reduction reaction in the future.     

Characterization and enhanced field emission properties of carbon nanotube bundle arrays coated with N-doped nanocrystalline anatase TiO2

Anatase TiO₂ nanocrystals (NCs) were deposited onto patterned carbon nanotube (CNT) bundle arrays to form a TiO₂/CNT composite using metal organic chemical vapor deposition (MOCVD) using titanium-tetraisopropoxide (Ti(OC₃H₇)₄) as a source reagent. The N-doped TiO₂/CNT composite was then fabricated using nitrogen plasma treatment. The structural and spectroscopic properties of TiO₂/CNT composites were characterized by field-emission scanning electron microscopy, micro-Raman spectroscopy and X-ray photoelectron spectroscopy. The combined geometrical structure and low electron affinity effects of N-doped TiO₂ led to a low turn-on field of 1.0 V μm⁻¹ at a current density of 10 μA cm⁻², a low threshold field of 1.9 V μm⁻¹ at a current density of 1 mA cm⁻², a high field enhancement factor of 3.0 × 10³, and long-term stability for the N-doped TiO₂/CNT composite. The results revealed that the N-doped TiO₂/CNT composite can be a potential candidate for field emission devices.     

Investigation of influence of synthesis parameters on length and purity of the carbon nanotubes

In this article, a systematic study was conducted to understand the influences of various synthesis parameters, such as catalyst pretreatment time, growth time, growth temperature, reaction gas flow rate on length and quality of the carbon nanotubes grown by thermal chemical vapor deposition (TCVD). Carbon nanotube (CNT) grown on Fe deposited on silicon substrates were characterized by scanning electron microscope and Raman spectroscopy. It was found that all of the synthesis parameters investigated had effects on both length and quality of the carbon nanotube. After optimizing the various thermal chemical vapor deposition synthesis parameters, long carbon nanotube arrays of up to 150 microm in length were successfully synthesized and possess the potential application in multi-level interconnects.