高纯度纳米碳管的低温合成

以甲醇为碳源,在负载于CaO上的Co催化剂的催化作用下,利用微波等离子体化学气相沉积法低温合成了较高纯度的纳米碳管.经分析认为,等离子体中因甲醇裂解产生的氧离子及含氧基团对无定形碳具有很强的选择性刻蚀能力,为低温合成纳米碳管时提高其纯度创造了条件.     

腔体压力对纳米碳管结构的影响

在镍催化剂的催化作用下，利用微波等离子体化学气相沉积法合成了纳米碳管，分析了不同腔体压：匀对所合成的碳材料结构的影响．研究表明，当腔体压力增大时，基片温度上升，有利于纳米碳管管状结构的形成，提高纳米碳管的石墨化程度．     

腔体压力对纳米碳管结构的影响

在镍催化剂的催化作用下,利用微波等离子体化学气相沉积法合成了纳米碳管,分析了不同腔体压力对所合成的碳材料结构的影响.研究表明,当腔体压力增大时,基片温度上升,有利于纳米碳管管状结构的形成,提高纳米碳管的石墨化程度.     

微波CVD法低温制备纳米金刚石薄膜

利用甲醇和氢气的混合气体，用微波等离子体CVD方法在480℃下成功地在硅片表面制备出纳米金刚石薄膜，本文研究了甲醇浓度和沉积温度对金刚石膜形貌的影响．通过Raman光谱、原子力显微镜及扫描隧道显微镜对样品的晶粒尺寸及质量进行了表征．研究结果表明：通过提高甲醇浓度和降低沉积温度可以在直径为50mm的硅片表面沉积高质量的纳米金刚石薄膜，晶粒尺寸大约为10～20nm，并对低温下沉积高质量的纳米金刚石薄膜的机理进行了讨论．     

Co/MgO固体催化剂CVD法合成单壁纳米碳管的研究

分别用浸渍法、离子吸附沉淀法、溶胶一凝胶法制备了四组Co／MgO催化剂．1000C时,这些催化剂均能在CH4气氛下合成单壁纳米碳管,产量受催化剂活性组分尺寸影响明显．经透射电子显微镜(TEM)和热重分析(TGA)结果发现,浸渍法中以乙醇作为溶剂制备的催化剂所制得的产物中含有最多的单壁纳米碳管;离子吸附沉淀法所得的催化剂因沉淀的活性组分颗粒过大而不适合于单壁纳米碳管的生长;溶胶一凝胶法通过优化工艺将有望获得高产率的制备单壁碳管的催化剂．TEM和电子衍射观测同时表明所制得的单壁纳米碳管的直径都分布在1nm左右,且大部分聚集成束．     

微波CVD法低温制备纳米金刚石薄膜

利用甲醇和氢气的混合气体,用微波等离子体CVD方法在480℃下成功地在硅片表面制备出纳米金刚石薄膜,本文研究了甲醇浓度和沉积温度对金刚石膜形貌的影响.通过Raman光谱、原子力显微镜及扫描隧道显微镜对样品的晶粒尺寸及质量进行了表征.研究结果表明:通过提高甲醇浓度和降低沉积温度可以在直径为50 mm的硅片表面沉积高质量的纳米金刚石薄膜,晶粒尺寸大约为10～20 nm,并对低温下沉积高质量的纳米金刚石薄膜的机理进行了讨论.     

掺氮对纳米金刚石薄膜形貌及组成结构的影响

采用微波等离子体化学气相沉积技术,通过在甲烷和氢气的混合反应气源中通入不同浓度的氮气,合成了氮掺杂的纳米金刚石薄膜.表征结果表明随着氮气浓度的增加,所得到的金刚石薄膜的材料特征发生了明显的改变:膜层晶粒结构由从未见过的大尺寸片状向团簇状再向微颗粒状转变,并且薄膜的表面粗糙度相应变小;同时薄膜中非金刚石组份逐渐增多,膜材的物相纯度下降.氮气浓度除决定了纳米金刚石薄膜中N的掺杂度外,还会对膜材的物相组成、形貌及结构产生巨大的影响.     

金刚石薄膜的低温沉积

采用乙醇和氢气作为工作气体，利用微波等离子体化学气相沉积法在较低的沉积温度下制备了金刚石薄膜，用扫描电子显微镜(SEM)、Raman光谱、X射线衍射仪(XRD)和红外光谱研究了薄膜的结构和性质。结果表明：在450℃的基片温度下，利用乙醇和氢气在优化的工艺条件下可得到具有微晶结构的金刚石薄膜。     

基片温度对纳米金刚石薄膜制备的影响

采用多模谐振腔微波等离子体CVD在不同基片温度下制备了纳米金刚石薄膜,通过扫描电子显微镜（SEM）、原子力显微镜（AFM）和拉曼光谱测试,研究了基片温度对纳米金刚石薄膜性能的影响.结果表明：在其他工艺条件不变时,基片温度对薄膜性能具有较大的影响,较低的基片温度更有利于制备高质量的纳米金刚石薄膜,实验所获得的优化基片温度为720℃左右.     

粉末冶金法制备纳米碳管增强铜基复合材料的研究

用化学镀在纳米碳管表面镀覆了铜及镍,并用粉末冶金法制备纳米碳管增强铜基复合材料,研究了制备工艺的有关参数对其性能的影响．结果表明：不同的工艺参数对复合材料的性能有不同影响,相对其它参数,纳米碳管体积分数显著影响复合材料的综合性能．纳米碳管体积含量在12％左右时,复合材料的致密度和硬度达到较好综合值。     

Effect of Particle Density on the Aligned Growth of Carbon Nanotubes

Aligned carbon nanotubes (CNTs) wre prepared on Ni-coated Ni substrate by microwave plasma chemical vapor deposition (MWPCV D) with a mixture of methane and hydrogen gases at temperature of 550℃ . The experimentul results show a direct correlation between the alignment of CNTs and the density of the catalyst particles at low, temperature, When the particle density is high enough, among CNTs there are strong interactions that can inhibit CNTs from growing randomly. The crowding effect among dense CNTs results in the aligned growth of CNTs at low temperature.     

碳纳米管的合成与制备

金属纳米颗粒和碳纳米管是两种重要的纳米材料,要实现碳纳米管的大批量制备,必须首先解决催化剂连续投放问题和催化剂与产物及时导出的问题.通过特殊的反应装置和工艺可以实现碳纳米管的连续制备,从而达到低成本大批量制备碳纳米管的目的.本文采用一个简单的方法合成了铁钴（Fe/Co）纳米颗粒,并采用化学气相沉积法实现了碳纳米管的批量合成,纳米颗粒的尺寸分布均匀,碳纳米管管径均匀、高纯度、结构完美.合成的碳纳米管机械强度高,同时还有独特的金属或半导体导电性.     

Natural Mineral-marine Manganese Nodule as a Novel Catalyst for the Synthesis of Carbon Nanotubes

1 IntroductionCarbon nanotubes (CNTs) are globally in the lime-light as a newfancy material of the 21st century andtheyare broadening their applications to almost all scientificareas . Several methods , such as arc-discharge va-porization[1],laser vaporization[2],chemical vapor depo-sition (CVD)[3-4]and others[5], have been developed tofabricate CNTs (including single and multi wall) up tonow.It is very well possible that the CVD method,be-cause of its simplicity andlowcost ,will provide …     

Synthesis of carbon nanotubes using Cu-Cr-O as catalyst by chemical vapor deposition

A novel powder catalyst Cu-Cr-O applied to the synthesis of carbon nanotubes(CNTs) was developed, which was prepared via ammonia precipitation method. Techniques of thermo-gravimetric/ differential scanning calorimeter(TG-DSC), X-ray diffraction(XRD) as well as scanning electron microscopy(SEM) and transmission electron microscopy(TEM) have been employed to characterize the thermal decomposition procedure, crystal phase and micro structural morphologies of the as-synthesized materials, respectively. The results show that carbon nanotubes are successfully synthesized using Cu-Cr-O as catalyst when the precursors are calcined at 400, 500, 600, and 700 ℃. The results indicate that the calcination of the Cu-Cr-O catalyst at 600 ℃ is an effective method to get MWCNT with few nano-tube defects or amorphous carbons.     

Synthesis of aligned carbon nanotubes by thermal chemical vapor deposition

Single crystal silicon was found to be very beneficial to the growth of aligned carbon nanotubes by chemical vapor deposition with C₂H₂ as carbon source. A thin film of Ni served as catalyst was deposited on the Si substrate by the K575X Peltier Cooled High Resolution Sputter Coater before growth. The growth properties of carbon nanotubes were studied as a function of the Ni catalyst layer thickness. The diameter, growth rate and areal density of the carbon nanotubes were controlled by the initial thickness of the catalyst layer. Steric hindrance between nanotubes forces them to grow in well-aligned manner at an initial stage of growth. Transmission electron microscope analysis revealed that nanotubes grew by a tip growth mechanism. Funded by the National Natural Science Foundation of China (No. 50435030)