共查询到19条相似文献,搜索用时 93 毫秒
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本文介绍了一种微图形化碳纳米管场发射阵列冷阴极,每个图形的直径仅为1μm,构成一个发射单元。制作工艺如下:首先在硅(100)基片上沉积氮化钛缓冲层,然后采用曝光工艺获得直径为1μm的胶孔阵列,沉积催化剂铁,最后采用直流等离子体增强化学气相沉积(DC-PECVD)生长直立的碳纳米管。并对17500个发射单元的阵列阴极进行了表面形貌表征及场发射特性测试。结果表明,碳纳米管阵列阴极的一致性较好;最低开启电场为1 V/μm;电场为17 V/μm时,测得的电流密度已达到90 mA/cm^2;发射电流为550μA时,在2.5 h内的波动小于5.6%。 相似文献
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定向碳纳米管阵列在石英玻璃基底上的模板化生长研究 总被引:5,自引:0,他引:5
分别以带有刻痕的石英玻璃和溅射过Au膜的石英玻璃为生长基底,通过催化裂解二茂铁和二甲苯混合物的方法,在基底上制备出了模板化的定向碳纳米管(CNT)阵列,扫描电镜(SEM)和透射电镜(TEM)观察表明:在这两种基底上生长的定向碳纳米管阵列的模板化程度都很高,其中的碳纳米管多为直径在20~50nm的多壁管(MWNT),且具有很好的定向性。本文还分析、对比了基底材料对定向碳纳米管生长的影响,初步探讨了定向碳纳米管模板化生长的形成机制。 相似文献
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采用反复机械拉伸法制备了单壁碳纳米管(SWCNTs)均匀分散且定向排列的SWCNT/聚甲基丙烯酸甲酯(PMMA)复合材料.将半干状态的SWCNT/PMMA复合体沿同一方向反复拉伸100次,每次的拉伸比为50,每次拉伸完以后,将聚合物沿拉伸的方向反复重叠.SEM,偏振拉曼光谱分析均表明SWCNTs沿拉伸方向排列.电学与力学测试结果表明:与PMMA相比,复合材料的电导率、弹性模最、拉伸强度和延伸率均得到明显提高,并表现出显著各向异性,复合材料滑拉伸方向的电学和力学性能显著高于其垂直于碳纳米管排列方向的值. 相似文献
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Hiroki Ago Ei-ichiro Uchimura Takeshi Saito Satoshi Ohshima Naoki Ishigami Masaharu Tsuji Motoo Yumura Masato Miyake 《Materials Letters》2006,60(29-30):3851-3854
We demonstrate that an aligned multi-walled carbon nanotube array can immobilize Hela cells through insertion of the nanotube tips into the cell. The cells were immobilized by pressing onto the nanotube array with the aid of mild centrifugal force. The nanotube array fixed a much larger number of cells compared with the flat surface of a Si substrate, indicating strong binding force of the aligned nanotubes toward the cell. This is the first example of mechanical cell immobilization, which offers future applications of the nanotube array for cellular biology, tissue engineering, and biomolecular devices. 相似文献
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以CVD法定向碳纳米管(ACNTs)阵列为骨架,利用化学气相渗透(CVI)工艺制备了新型定向碳纳米管/炭(ACNT/C)纳米复合材料。通过偏光金相显微镜(PLM)、扫描电子显微镜(SEM)、高分辨透射电子显微镜(HRTEM)、X射线衍射(XRD)和Raman光谱等分析方法对其显微结构和热解炭沉积机理进行了研究。结果表明:所制ACNT/C纳米复合材料的热解炭结构主要为类粗糙层结构,围绕碳纳米管生长的热解炭石墨层片结构清晰,并且碳纳米管和热解炭之间具有良好的界面结合;而在相同工艺条件下围绕炭纤维生长的热解炭为典型的光滑层结构。这可能是由于在热解炭沉积过程中存在碳纳米管"诱导"沉积过程,即沿着碳纳米管径向的离域化共轭π键和具有类似结构的芳香族大分子通过π-π非共价键作用相结合,并在CNTs纳米尺寸的影响下,芳香族大分子按照"软取向"(Softepitaxy)围绕碳纳米管生成环形层片状类石墨结构的热解炭。该研究结果有望为热解炭的可控沉积起到一定的借鉴作用。 相似文献
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空气氧化法提纯碳纳米管的研究 总被引:3,自引:3,他引:3
以乙炔为原料气,采用铁-镍复合催化剂,在700℃下,由化学气相沉积法(CVD)制得了直径为10nm~30nm的多壁碳纳米管(MWNT)。然后通过空气氧化法对所获碳纳米管进行提纯,去除了碳纳米管中的无定形炭、炭纳米颗粒及炭纤维等非晶碳成分,提高了碳纳米管的纯度;并研究了提纯温度和时间的关系。结果表明:碳纳米管在空气中440℃加热3h后,烧损率趋于平稳,基本上稳定在2%左右。使用透射电镜(TEM)考察提纯前后碳纳米管的形貌,发现碳纳米管在空气中440℃加热3h后,非晶碳成分基本去除,纯度得到提高。 相似文献
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Slawomir Boncel Krzysztof K.K. Koziol Krzysztof Z. WalczakAlan H. Windle Milo S.P. Shaffer 《Materials Letters》2011,65(14):2299-2303
Highly aligned carbon nanotube/polystyrene (HACNT/PS) composites were prepared conveniently via polymer impregnation of aligned arrays, avoiding conventional solution or melt processes that involve high-shear blending. Detailed scanning electron microscopy (SEM), X-Ray diffraction (XRD) and differential scanning calorimetry (DSC) studies show that the alignment of the multi-wall nanotubes is retained after polymer impregnation. A range of key parameters were investigated, including the amount of molten polymer required for complete infiltration, the maximum mass fraction of CNTs in dense composites, and the effect of CNTs on the glass transition temperature (Tg) of the polymer. This approach may be adapted to the fabrication of large scale, highly anisotropic, thin or multilayer CNT composites using other molten polymers. 相似文献
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5?mm long aligned titanium oxide/carbon nanotube (TiO(2)/CNT) coaxial nanowire arrays have been prepared by electrochemically coating the constituent CNTs with a uniform layer of highly crystalline anatase TiO(2) nanoparticles. While the presence of the TiO(2) coating was confirmed by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy and x-ray diffraction, the resultant TiO(2)/CNT coaxial arrays were demonstrated to exhibit minimized recombination of photoinduced electron-hole pairs and fast electron transfer from the long TiO(2)/CNT arrays to external circuits. This, in conjunction with the aligned macrostructure, facilitates the fabrication of TiO(2)/CNT arrays for various device applications, ranging from photodetectors to photocatalytic systems. Thus, the millimeter long TiO(2)/CNT arrays represent a significant advance in the development of new macroscopic photoelectronic nanomaterials attractive for a variety of device applications beyond those demonstrated in this study. 相似文献
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High-quality carbon nanotube (CNT) arrays composed of nanotubes with different diameters and wall numbers were synthesized by water-assisted chemical vapor deposition (CVD) from engineered Fe catalysts. Interestingly, the distribution of nanotube diameter and wall number broadened over 2.5 times as the catalytic Fe thickness increased. The mean diameter and wall number of nanotubes increased monotonically with the Fe thickness, while the calculated CNT area density within an array dropped about 32 times. Field emission measurements revealed that the turn-on voltage for CNT arrays decreased from 3.5 to 2.5 V/µm with the increased catalytic Fe thickness. It was believed that the screening effect from the proximity of neighboring nanotubes has a dominant influence than the CNT diameter on the resulting turn-on voltage. 相似文献