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采用冷壁装置化学气相沉积(CVD)制备纳米碳管,以乙炔(C2H2)为碳源气体,研究了2种催化剂(镍、铁)、3种基底、3种稀释气体、3种稀释气体和碳源气体流量比以及温度对CVD法生长纳米碳管的影响,用SEM和TEM分析了产物的形貌.结果表明,镍催化活性高于铁的催化活性.与石墨和纯铁基底相比,以单晶硅基底生长的纳米碳管纯度更高,管壁更干净.3种稀释气体和碳源气体流量比(2/1、10/1、19/1)中,以流量比为10/1时生长纳米碳管效果最好.3种稀释气体(氨气、氢气、氮气)中,以氨气最好.随着生长温度的升高,催化剂的活性提高,有利于碳的有序排列,但生长的碳纳米管直径增大.当基底为单晶硅、催化剂镍膜厚度为20nm、氨气气氛、生长温度为850℃时,得到了近似定向生长的纳米碳管. 相似文献
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射频磁控溅射室温下制备ITO薄膜的光学性能研究 总被引:3,自引:0,他引:3
靶材为铟锡氧化物(In2O3:SnO2=1:1),用射频磁控溅射法在低温下制备了光电性能优良的ITO薄膜.质量流量计调节Ar气压强为0.2~3.0Pa,氧流量为0~10sccm,并详细探讨了溅射时氩气压强和氧流量变化对ITO薄膜光学性能的影响.结果表明:溅射Ar气压强为0.8Pa,氧流量为2.4sccm时,薄膜的折射率最低n=1.97,较接近增透膜的光学匹配.薄膜厚度为241.5nm时,薄膜的最大透过率为89.4%(包括玻璃基体),方阻为75.9Ω/□,电导率为8.8×10-4Ω·cm. 相似文献
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采用等离子体增强化学气相沉积技术,以C2H2、H2和N2为反应气体,制备出碳纳米管薄膜。利用扫描电镜和拉曼光谱仪对其进行表征。结果表明:氢气流量对碳纳米管薄膜的生长起着重要作用,获得分布均匀、密度适中、杂质缺陷少的碳纳米管的最佳氢气流量为30 sccm。 相似文献
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利用微波等离子体化学气相沉积(MPCVD)法在黑硅和抛光单晶硅片衬底上生长非晶碳薄膜,其中变量为CH4流量,分别为10sccm、14sccm、18sccm、22sccm、26sccm.通过扫描电子显微镜(SEM)、X射线衍射分析(XRD)、原子力显微镜(AFM)、拉曼光谱表征了非晶碳薄膜的结构和形貌特征.结果表明,在650℃时随着CH4流量的逐渐增加,在平整的非晶碳薄膜上C-C的sp2相团簇颗粒的直径逐渐变大.AFM测试结果显示,非晶碳薄膜表面的平均粗糙度(Ra)为0.494nm. 相似文献
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微波-ECR等离子体辅助沉积Zr-N薄膜结构和性能研究 总被引:2,自引:1,他引:2
在不同氮流量下,利用微波-ECR等离子体溅射沉积技术在45#钢基体上制备了ZrN薄膜.XRD、TEM分析结果表明:随着充入N2流量的改变,薄膜结构由单一的ZrN结构向ZrN和ZrNx复合结构转变,然后出现非晶态结构.当N2流量在(2~8) sccm之间,薄膜为ZrN结构;在(10~12) sccm时,为ZrN和正交的ZrNx(a=0.3585 nm,b=0.4443 nm,c=0.5798 nm)混合型结构;14 sccm时出现非晶化趋势.俄歇电子谱仪(AES)和探针分析表明:薄膜中氮含量为7.73%~66.96%.同时对薄膜的硬度进行了测试,薄膜硬度在19.82 GPa~26.32 GPa之间,随氮值的变化,先增加后降低.对硬度最高的4#样品进行了摩擦性能测试,磨损率约4.5×10-8 mg/min.薄膜这些性能的变化是由于不同氮流量下薄膜结构发生变化造成的. 相似文献
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金属铀的化学性质十分活泼, 极易发生氧化腐蚀. 为改善基体的抗腐蚀性能, 采用非平衡磁控溅射技术在金属铀表面制备了不同氮含量的CrNx薄膜. 采用扫描电子显微镜(SEM)、X射线衍射技术(XRD)、X射线光电子能谱(XPS)、动电位极化曲线, 分别研究了薄膜形貌、物相结构、表面元素化学价态及抗腐蚀性能. 结果表明, 当氮流量为10 sccm时薄膜主要为体心立方的α-Cr, 随氮流量的增大, 薄膜转化为六方Cr2N和立方CrN结构, 其择优取向由Cr(110)转化为Cr2N(111)及CrN(200), 金属态Cr的含量逐渐减少, 氮化态Cr的含量增多, Cr2p3/2的结合能峰位逐渐向高结合能方向移动. CrNx薄膜呈纤维状结构, 当氮流量增大到30 sccm时, 生成了Cr2N的密排结构, 有效改善了薄膜的致密性. 在金属铀表面制备CrNx薄膜后, 自然腐蚀电位增大, 腐蚀电流密度降低, 当氮流量增大到30 sccm时, 薄膜的自然腐蚀电位提高了近550 mV左右, 腐蚀电流密度降低约两个数量级, 有效改善了贫铀表面的抗腐蚀性能. 相似文献
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探索了纯石墨电极在水中放电制备洋葱状富勒烯(Onion-like fullerenes,OLFs)的过程和工艺。用高分辨透射电镜(High resolution transmission electron microscope。HRTEM)对生成的OLFs进行了形貌、结构的观察与表征。分析结果表明制得的OLFs具有各种不同形状的内核。石墨化程度很高,直径分布在5nm~40nm范围内。在一定范围内随着电流强度的增大OLFs的产量和产率都有不同程度的提高。 相似文献
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Effect of acetylene flow rate on morphology and structure of carbon nanotube thick films grown by thermal chemical vapor deposition 总被引:1,自引:0,他引:1
Cao Zhangyi Sun Zhuo Guo Pingsheng Chen Yiwei 《Frontiers of Materials Science in China》2007,1(1):92-96
Carbon nanotube (CNT) films were grown on nickel foil substrates by thermal chemical vapor deposition (CVD) with acetylene
and hydrogen as the precursors. The morphology and structure of CNTs depending on the acetylene flow rate were characterized
by a scanning electron microscope (SEM), a transmission electron microscope (TEM) and a Raman spectrometer, respectively.
The effect of acetylene flow rate on the morphology and structure of CNT films was investigated. By increasing the acetylene
flow rate from 10 to 90 sccm (standard cubic centimeter per minute), the yield and the diameter of CNTs increase. Also, the
defects and amorphous phase in CNT films increase with increasing acetylene flow rate.
Translated from Journal of Inorganic Materials, 2006, 21(1): 75–80 [译自: 无机材料学报] 相似文献
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It is the purpose of this study to evaluate the field emission property of carbon nanotubes (CNTs) prepared by microwave plasma-enhanced chemical vapor deposition (MPCVD) method. Nickel layer of 5 nm in thickness on 20-nm thickness titanium nitride film was transformed into discrete islands after hydrogen plasma pretreatment. CNTs were then grown up on Ni-coated areas by MPCVD. Through the practice of Taguchi method, superior CNT films with very low emission onset electric field, about 0.7 V/μm (at J = 10 μA/cm2), are attained without post-deposition treatment. It is found that microwave power has the most important influence on the field emission characteristics of CNT films. The increase of methane flow ratio will downgrade the degree of graphitization of CNT and thus its field emission characteristics. Scanning electron microscope and transmission electron microscopy (TEM) observation and energy dispersive X-ray spectrometer analysis reveal that CNT growth by MPCVD is based on tip-growth mechanism. TEM micrographs validate the hollow, bamboo-like structure of the multi-walled CNTs. 相似文献
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Nitrogen-doped carbon nanotube (CNT) films have been synthesized by simple microwave plasma enhanced chemical vapor deposition technique. The morphology and structures were investigated by scanning electron microscopy and high resolution transmission electron microscopy. Morphology of the films was found to be greatly affected by the nature of the substrates. Vertically aligned CNTs were observed on mirror polished Si substrates. On the other hand, randomly oriented flower like morphology of CNTs was found on mechanically polished ones. All the CNTs were found to have bamboo structure with very sharp tips. These films showed very good field emission characteristics with threshold field in the range of 2.65-3.55 V/μm. CNT film with flower like morphology showed lower threshold field as compared to vertically aligned structures. Open graphite edges on the side surface of the bamboo-shaped CNT are suggested to enhance the field emission characteristics which may act as additional emission sites. 相似文献
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Carbon nanotubes (CNTs) are a promising material for superhydrophobic coating. In the present study, we prepared superhydrophobic CNT films by spraying CNT dispersions, and discussed the factors that control superhydrophobicity of the CNT films. Three types of dispersions (i.e., CNTs/ethanol, CNTs functionalized with dodecyl groups/ethanol, and CNTs and trimethylsiloxysilicate (TMSS)/ethanol) were prepared as spraying solutions. As increasing the amount of spray-coated CNTs, hydrophobicity of the resulting films became higher, and eventually superhydrophobicity was observed. The spray-coated CNT films had hierarchical roughness, which is preferable morphology to show superhydrophobicity. The coexistence of TMSS in the film lowered the amount of CNTs required to show superhydrophobicity because TMSS acted like glue that prevented CNTs from aggregating on substrates. Interaction force of CNTs also affected the wettability of the CNT films. The π–π interaction of CNTs resulted in the aggregation of them on substrates, which lowered the wettability of the films. From this viewpoint, functionalization of CNTs with dodecyl groups was effective to form superhydrophobic films because the dodecyl groups on CNTs screened the π–π interaction of CNTs. 相似文献
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Roerdink M Pragt J Korczagin I Hempenius MA Stöckli T Keles Y Knapp HF Hinderling C Vancso GJ 《Journal of nanoscience and nanotechnology》2007,7(3):1052-1058
Block copolymer thin films fabricated from polystyrene-polyferrocenylsilane (PS-b-PFS) block copolymers on silicon substrates were used as precursors of well-ordered, nanosized growth catalysts for carbon nanotubes (CNTs). The size of the catalytic domains was tuned by changing the molecular weight of the block copolymer, enabling control of the diameter of the CNTs grown from these substrates. CNT growth on catalytic substrates with larger organometallic domain sizes, using acetylene as a carbon source, resulted in enhanced amounts of CNT deposition compared to smaller PFS domains, which exhibited low catalytic activity. The inner and outer diameters of the multi-walled CNTs obtained were typically 8 and 16 nm, respectively, and were not influenced by the catalytic domain sizes. Various annealing strategies in inert or in hydrogen atmosphere were investigated. The use acetylene with an additional hydrogen flow as gas feed resulted in a significant increase in deposition on all PS-b-PFS decorated substrates. Under these conditions, the CNT diameters could be controlled by the catalyst domain sizes, resulting in decreasing diameters with decreasing domain sizes. Multiwalled CNTs with inner and outer diameters of 4 and 7 nm, respectively, and a narrow diameter distribution were obtained. 相似文献
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Growth of carbon nanotubes on cobalt catalyst film using electron cyclotron resonance chemical vapour deposition without thermal heating 总被引:1,自引:0,他引:1
This paper demonstrates that carbon nanotubes (CNTs) can be synthesized on a cobalt coated silicon substrate using electron cyclotron chemical vapour deposition and without intentionally heating the substrate. With the mixed gases of C(3)H(8)/N(2), CNTs with a multi-walled structure and a diameter up to 70?nm have been observed. Results show that the diameter of the CNTs increases with the thickness of the cobalt catalyst film and the amount of nitrogen incorporated in the CNT films considerably influences the structures of the CNTs. Vertically aligned CNTs can be fabricated with a microwave power as low as 300?W and the flow rate ratio of C(3)H(8)/N(2) = 20/20?sccm. The CNTs exhibit a turn-on field of 0.2?V?μm(-1) determined at the emission current density of 10?μA?cm(-2). 相似文献
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Walid M. Daoush Byung K. Lim Dong H. Nam Soon H. Hong 《Journal of Experimental Nanoscience》2014,9(6):588-596
Carbon nanotube/silver (CNT/Ag) nanocomposites include CNT volume fraction up to 10?vol.% were prepared by chemical reduction in solution followed by spark plasma sintering. Multiwalled CNTs underwent surface modifications by acid treatments, the Fourier transform infrared spectroscopy data indicated several functional groups loaded on the CNT surface by acid functionalisation. The acid-treated CNTs were sensitised and activated. Silver was deposited on the surface of the activated CNTs by chemical reduction of alkaline silver nitrate solution at room temperature. The microstructures of the prepared CNT/Ag nanocomposite powders were investigated by high-resolution scanning electron microscopy (HRSEM), transmission electron microscopy and X-ray powder diffraction analysis. The results indicated that the produced CNT/Ag nanocomposite powders have coated type morphology. The produced CNT/Ag nanocomposite powders were sintered by spark plasma sintering. It was observed from the microstructure investigations of the sintered materials by HRSEM that the CNTs were distributed in the silver matrix with good homogeneity. The hardness and the tensile properties of the produced CNT/Ag nanocomposites were measured. By increasing the volume fraction of CNTs in the silver matrix, the hardness values increased but the elongation values of the prepared CNT/Ag nanocomposites decreased. In addition, the tensile strength was increased by increasing the CNTs volume fraction up to 7.5?vol.%, but the sample composed of 10?vol.% CNT/Ag was fractured before yielding. 相似文献
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Behzad Karimi Amir Masoud Arabi Farhood Najafi Mahdi Shafiee Afarani 《Journal of Materials Science: Materials in Electronics》2018,29(16):13499-13507
In this study, synthesis of carbon nanotube (CNT)–CdSe Quantum dots (QDs) nanocomposites has been investigated. CdSe QDs were synthesized via hydrothermal process. The chemical tendency of CNT and QDS was increased by precipitation after surface functionalization of CNTs (by carboxylated groups) and CdSe QDs (by silane groups), separately. The structure of nanocomposites was amorphous with a little amount of nanocrystalline cubic CdSe. The Fourier-transform infrared (FTIR) spectra and Raman spectrum revealed the strong chemical tendency of linkage between CNTs and QDs after functionalization on the surface of them. The morphology of nanocomposites depended on the QDs concentration and changed from aggregates of CNTs to the marvelous decoration of quantum dots on the ropes of CNTs. Transmission electron microscope (TEM) and atomic force microscope (AFM) images confirmed the adorable coatings of CNTs with CdSe QDs. The nanocomposites emitted in blue–green region with a maximum peak at 490 nm under the exposure of Ultraviolet (UV) light. Below 50 wt% QDs, the emission was quenched completely. 相似文献
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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. 相似文献
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X-ray imaging data obtained from cold cathodes using gallium-doped zinc oxide (GZO)-coated CNT emitters are presented. Multi-walled CNTs were directly grown on conical-type (250 μm-diameter) tungsten-tip substrates at 700 °C via inductively coupled plasma-chemical vapor deposition (ICP-CVD). GZO films were deposited on the grown CNTs at room temperature using a pulsed laser deposition (PLD) technique. Field-emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM) were used to monitor the variations in the morphology and microstructure of the CNTs before and after GZO coating. The formation of the GZO layers on the CNTs was confirmed using energy-dispersive X-ray spectroscopy (EDX). The CNT-emitter that was coated with a 10-nm-thick GZO film displayed an excellent performance, such as a maximum emission current of 258 μA (at an applied field of 4 V/μm) and a threshold field of 2.20 V/μm (at an emission current of 1.0 μA). The electric-field emission characteristics of the GZO-coated CNT emitter and of the pristine (i.e., non-coated) CNT emitter were compared, and the images from an X-ray system were obtained by using the GZO-coated CNT emitter as the cold cathode for X-ray generation. 相似文献