共查询到19条相似文献,搜索用时 203 毫秒
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采用化学气相沉积法(chemical vapor deposition)制备碳纳米管.在高温裂解甲烷制备碳纳米管的反应体系中,比较研究了碳酸钠、碳酸钾、碳酸钙和碳酸钡等碳酸盐作为毒物对镍基催化剂和碳纳米管的影响;另外,还考察了裂解温度对碳纳米管的产率和管型的影响。实验中采用气相色谱(gas chromatography)在线检测甲烷的转化率,从而比较镍基催化荆的催化活性;采用透射电子显微镜(transmission electron microscopy)对合成的碳纳米管的外部形貌进行观察。结果发现,无论是从碳纳米管的产率还是形貌,碳酸钠均优于其它几种碳酸盐,内管径可达到70-80nm,另外还发现,750℃为此法制备碳纳米管的最佳裂解温度。 相似文献
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钴/碳纳米管催化剂CVD法制备碳纳米管 总被引:2,自引:0,他引:2
以乙烯为碳源、多壁碳纳米管为载体负载钴作为催化剂,利用CVD法制备出了高质量的多壁碳纳米管.利用扫描电子显微镜(SEM)对催化剂的形貌进行了表征,利用透射电子显微镜(TEM)、X射线衍射仪(XRD)以及差热-热重(TG-DTA)方法对产物进行了表征.发现在最佳裂解温度770℃下制备的多壁碳纳米管直径分布均匀、曲率小、纯净、产率高,更重要的是不具有难处理的氧化物(如Al2O3)载体,充分体现了碳纳米管作为载体的优越性. 相似文献
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衬底温度对碳纳米管生长和结构的影响 总被引:2,自引:0,他引:2
用CH4、NH3和H2为反应气体,利用等离子体增强热丝化学气相沉积在沉积有Ta缓冲层和Ni催化剂层的Si衬底上制备了准直碳纳米管,并用扫描电子显微镜和透射电子显微镜研究了它们的生长和结构随温度的变化.结果表明生长的准直碳纳米管是竹节型结构,其直径随衬底温度的降低而减小,生长速率随衬底温度的升高有一极值.从催化剂在衬底温度作用下的变化开始,分析了衬底温度对碳纳米管生长和结构的影响. 相似文献
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为了满足各种纳米电子学应用的需求,发展新的制备碳纳米管的方法引起人们特别的关注。最近,作者研究了乙醇催化化学气相沉积法来制备多壁碳纳米管。然而,这种方法需要使用金属催化剂,这使得产物中带有杂质。提出了一种采用将赤热石墨棒在乙醇中快速淬火制备多壁碳纳米管的方法,利用这种方法制备的碳纳米管没有催化剂杂质。利用高分辨透射电子显微术对制备的碳纳米管进行了表征。实验结果表明,制备的产物是多壁碳纳米管。由于这种方法制备碳纳米管不需要催化剂,因此它是一种经济的制备碳纳米管的方法。 相似文献
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利用介质阻挡放电等离子体化学气相沉积技术,在蒸镀有13nm Ni催化剂层的Si基材上,以CH4为碳源,H2与NH3的混和物为刻蚀和稀释气体,在630和750℃的不同温度条件下合成碳纳米管。实验研究了不同氨气比例条件下碳纳米管的生长情况,并给出了合成碳纳米管的最佳氨气含量区间,SEM和TEM测试发现,所合成的碳纳米管具有竹节型结构,Ni催化剂形貌表明碳纳米管生长符合顶端机制,实验还发现氨气含量对碳纳米管的生长影响很大,并对其原因进行了初步的分析. 相似文献
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等离子体射流法制备高纯竹节状碳纳米管 总被引:1,自引:0,他引:1
以乙醇为碳源,二茂铁为催化剂,氮气为电弧工作气体,利用等离子体射流在常压下制备高纯度竹节状多壁碳纳米管。用TEM和HRTEM等技术对所得产品进行表征。发现在电弧电压140V~150V,电流220A~240A,将二茂铁和乙醇混合溶液(质量比为1:100)以50mL/min速度连续加入反应器,反应120S后,即可批量制备纯度在90%以上的竹节状碳纳米管;这些竹节状碳纳米管的管径尺寸均匀,为20nm左右,长度为数微米,其管壁呈典型的鱼骨状。产品中含有部分分叉结构,呈Y形竹节状碳纳米管。认为竹节状碳纳米管的形成涉及以下几个步骤:乙醇在等离子体射流中裂解产生大量碳活性物种,同时溶解在乙醇中的二茂铁生成催化剂颗粒:碳活性物种在催化剂颗粒上溶解、扩散并从催化剂颗粒上析出堆积成为碳纳米管管壁碳层,由于催化剂颗粒运动与碳层生长速度的差异,最终形成竹节状结构的碳纳米管。 相似文献
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以二甲硫醚为碳源,Fe/MgO为催化剂,采用化学气相沉积法制备了碳纳米管。通过SEM、Raman、XRD、TEM表征方法研究了实验合成条件对碳纳米管产物的形貌和微结构的影响。结果表明,二甲硫醚的蒸汽浓度对碳纳米管的形貌和产量有重要影响。较高的二甲硫醚浓度会使催化剂的活性降低,制备出的碳纳米管较短且石墨化程度也较差。生长碳纳米管的最佳二甲硫醚浓度范围为2.69%~3.86%,且碳纳米管产物中有Y型碳纳米管的生成,并对其生长机理进行了初步讨论。 相似文献
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Multiwall carbon nanotubes have been synthesized on silicon substrates via atmospheric pressure chemical vapour deposition technique using bismuth as a catalyst. Field emission scanning electron microscopy analysis suggests that the samples grow through a tip growth mechanism. High-resolution transmission electron microscopy analysis shows spaghetti-like multiwall carbon nanotubes and with a bamboo-like structure obtained using the Bi catalyst. The quality, in terms of the graphitic crystallinity of the as grown carbon nanotubes, was analyzed by Raman analysis. The study shows that the catalyst, namely bismuth strongly influences the growth density and graphitic crystallinity of the grown carbon nanotubes. 相似文献
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Bin Xue Run Liu Wan-Zhen Huang Yi-Fan Zheng Zhu-De Xu 《Journal of Materials Science》2009,44(15):4040-4046
The growth of bamboo-like multiwalled carbon nanotubes (MWCNTs) over Cu/Al2O3 catalyst by chemical vapor deposition under atmospheric pressure using ethanol as the carbon source has been demonstrated.
The obtained MWCNTs are dominant with bamboo-like morphology. The morphologies, graphitization degree, and microstructures
of the products were characterized by transmission electron microscopy, X-ray diffraction, Raman spectroscopy, field emission
scanning electron microscopy, high-resolution transmission electron microscopy, and selected area electron diffraction. The
results show that the combination of Cu/Al2O3 catalyst and ethanol was critical for the growth of bamboo-like MWCNTs. The possible factors causing the formation of bamboo-like
structures were also discussed. 相似文献
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Sadanadan B Savage T Bhattacharya S Tritt T Cassell A Meyyappan M Dai ZR Wang ZL Zidan R Rao AM 《Journal of nanoscience and nanotechnology》2003,3(1-2):99-103
We have previously shown that high-purity multiwalled carbon nanotubes (pristine MWNTs) can be prepared from a mixture of xylene-ferrocene (99 at% C:1 at% Fe) inside a quartz tube reactor operating at approximately 700 degrees C. In a similar process, approximately 3 g of melamine (C3H6N6) was introduced during the growth of MWNTs to prepare nitrogen-doped nanotubes. The structural and electronic properties of nitrogen-doped MWNTs were determined by scanning electron microscopy, high-resolution transmission electron microscopy (HRTEM), electron energy loss spectroscopy (EELS), and thermopower measurements. The individual nitrogen-doped nanotube exhibits a bamboo-like structure and comprises 6-16 tube walls, as evidenced by HRTEM studies. The EELS measurements yielded an average nitrogen content of approximately 5 at% in the doped tubes. The thermoelectric power data of nitrogen-doped MWNTs remained negative even after exposure to oxygen for an extended period of time, suggesting that nitrogen doping of MWNTs renders them n-type, consistent with scanning tunneling spectroscopic studies on similar nanotubes. 相似文献
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Synthesis of boron nitride nanotubes from boron oxide by ball milling and annealing process 总被引:1,自引:0,他引:1
Boron nitride nanotubes were synthesized from boron oxide by high-energy ball milling and annealing method. The diameter of the nanotubes is in the range of 20-200 nm. The nanotubes show a bamboo-like structure and cylindrical-like structure under low magnification. The shorter bamboo nodes with distinct knots were observed for the bamboo-like nanotubes with larger diameters and the knots can also occasionally be observed in the cylindrical-like BN nanotubes with smaller diameters under high magnification. Al and Si were found to be catalytic materials responsible for the formation of BN nanotubes besides the metallic particles containing Fe, Ni and Cr. 相似文献
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以乙醇、甲醇及液化石油气为碳源,低碳钢及含Ni合金钢等为基板,采用火焰法成功地制备出了一维碳纳米材料,包括碳纳米管(CNTs)和一种新的“实心”碳纳米纤维(CNFs)。利用场发射枪高分辨扫描电镜(SEM)、透射电镜(TEM)和激光Raman光谱对碳纳米材料的结构进行了表征。发现基板材料决定燃烧生成物的性质,含Fe元素及其化合物的基板材料倾向于合成“实心”碳纳米纤维,而含Nj元素及其化合物的基板材料倾向于合成“空心”的碳纳米管,认为这是由于碳与Fe的亲和力比Ni大而造成的。不同碳源对一维碳纳米材料的形态也有影响,这与它们的含碳量和燃烧热等不同有关。 相似文献