共查询到20条相似文献,搜索用时 15 毫秒
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Pervaiz Ahmad Yusoff Mohd Amin Ziaul Raza Khan 《Materials and Manufacturing Processes》2015,30(2):184-188
Boron nitride microtubes are synthesized in a dual zone quartz tube furnace at 1200°C with ammonia as a reaction atmosphere. Field emission scanning electron microscopy (FE-SEM) results show a unique cone-like morphology of the tubes with larger internal space and thin walls structure. The diameters of the tubes were found to be in the range of 1 to ~2 µm with the walls thickness estimated to be from 10 to 100 nm. XPS survey shows N 1 s and B 1 s peaks at 398.7 and 191 eV, respectively, that represent h-BN in the sample. Raman spectroscopy indicates a high-intensity peak at 1372.53 (cm?1) that corresponds to the E2g mode of h-BN. Along with the novel tubular morphology of boron nitride microtubes, the present work also explains a mechanism for the formation of boron nitride nanosheets (from boron nitride microtubes) found in the FE-SEM results of the current sample. 相似文献
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M.R.Atiyah D.R.Awang Biak F.Ahmadun I.S.Ahamad F.Mohd Yasin H.Mohamed Yusoff 《材料科学技术学报》2011,(4):296-300
Synthesis of carbon nanotubes (CNTs) below 600℃ using supporting catalyst chemical vapor deposition method was reported by many research groups.However,the floating catalyst chemical vapor deposition received less attention due to imperfect nanotubes produced.In this work,the effects of varying the preheating temperature on the synthesis of CNT were investigated.The reaction temperature was set at 570℃.The preheating set temperature was varied from 150 to 400℃ at 50℃ interval.Three O-ring shape heating mantels were used as heating source for the preheater.In situ monitoring device was used to observe the temperature profile in the reactor.Benzene and ferrocene were used as the carbon source and catalyst precursor,respectively.Vertically aligned CNTs were synthesized when the preheating temperature was set at 400℃.When the preheating temperature was increased up to 400℃,both the length and the alignment of CNTs produced were improved. 相似文献
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将无定形硼粉于流动氨气(50 mL/min)和不同氧气流量(10、15、20、40 mL/min)的混合气氛下高温(1300℃)处理后, 在不锈钢基片上收集到白色棉花状产物。研究结果表明, 微量的氧气可将硼粉氧化成气态的B2O2中间体, 为BN纳米管的生长提供活性较高的硼源。当氧气流量适中时, 所得纳米管的平均直径为80 nm, 长度可达几百微米。氧气流量对BN纳米管的直径和产量影响较大, 纳米管直径随着氧气流量的增大而增大, 产量则出现先升高后降低的趋势。氮化硼纳米管的生长机理属于气-液-固模型。 相似文献
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Nanyang Wang Liping Ding Taotao Li Kai Zhang Liyun Wu Zhengyang Zhou Qian He Xuhua He Xuebin Wang Yue Hu Feng Ding Jin Zhang Yagang Yao 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(14):2206933
The large-scale synthesis of high-quality boron nitride nanotubes (BNNTs) has attracted considerable interests due to their applications in nanocomposites, thermal management, and so on. Despite decades of development, efficient preparation of high-quality BNNTs, which relies on the effective design of precursors and catalysts and deep insights into the catalytic mechanisms, is still urgently needed. Here, a self-catalytic process is designed to grow high-quality BNNTs using ternary W–B–Li compounds. W–B–Li compounds provide boron source and catalyst for BNNTs growth. High-quality BNNTs are successfully obtained via this approach. Density functional theory-based molecular dynamics (DFT-MD) simulations demonstrate that the Li intercalation into the lattice of W2B5 promotes the formation of W–B–Li liquid and facilitates the compound evaporation for efficient BNNTs growth. This work demonstrates a high-efficient self-catalytic growth of high-quality BNNTs via ternary W–B–Li compounds, providing a new understanding of high-quality BNNTs growth. 相似文献
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通过金属有机物化学气相沉积方法在碳纳米管模板上生长氮化镓纳米线束.对所生长的纳米结构进行了扫描电镜和X射线能谱分析,结果显示氮化镓纳米晶体可以与碳纳米管形成纳米线束状复合物.纳米线束状复合物直径为100~200 nm,长度为1.5~2.5μm,纳米线的两端呈现尖角状.由于氨气很容易吸附在碳纳米管表面,可知所获得的纳米结构的初始生长机制为碳纳米管的表面氮化.该研究也证明金属有机物化学气相沉积将是用于制造化合物纳米结构材料的一项有效的技术. 相似文献
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Formation and Structure of Boron Nitride Nanotubes 总被引:1,自引:0,他引:1
Jiang ZHANG Zongquan LI Jin XU Department of Materials Science Engineering Zhejiang University Hangzhou China State Key Laboratory of Silicon Materials Zhejiang University Hangzhou ChinaProf. 《材料科学技术学报》2005,21(1):128-130
Boron nitride (BN) nanotubes were simply synthesized by heating well-mixed boric acid, urea and iron nitrate powders at 1000℃. A small amount of BN nanowires was also obtained in the resultants. The morphological and structural characters of the BN nanostructures were studied using transmission electron microscopy. Other novel BN nanos-tructures, such as Y-junction nanotubes and bamboo-like nanotubes, were simultaneously observed. The growth mechanism of the BN nanotubes was discussed briefly. 相似文献
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Vl. A. Margulis O. V. Boyarkina L. V. Fomina E. A. Gaiduk E. E. Muryumin 《Fullerenes, Nanotubes and Carbon Nanostructures》2006,14(2):239-242
A simple model based on an effective-mass approximation is developed to describe the dispersion behavior of the linear optical susceptibility χ1 of an array of aligned, identical single-walled boron nitride nanotubes (BNNTs) in the spectral range where interband π-electron transitions dominate. An analytic closed-form expression for χ(1) valid in the low-frequency part of the spectrum is obtained in terms of the band gap Δg of BNNTs and the π-electron transfer integral Vppπ. To the best of our knowledge, the present analytic calculation is the first for such nanotubes. 相似文献
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Finite Element Modeling of Compressive Deformation of Super-long Vertically Aligned Carbon Nanotubes
The super-long, vertically aligned carbon nanotubes (SL-VACNTs) are novel carbon nanomaterial produced from template-free synthesis. The mechanical responses of such material have been investigated by continuum finite element modeling and compared with experimental observations. The crushable foam model has been adequate in modeling the stress-strain curve and deformation of the SL-VACNTs under compression. SL-VACNTs are seen to exhibit transient elastic deformation at small displacement and then plastic deformation at large displacement. The deformation mostly occur at the position immediately beneath the compression platen (indenter face) due to the high stress/strain concentrations. 相似文献
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《Fullerenes, Nanotubes and Carbon Nanostructures》2007,15(2):135-143
Fe-filled multi-wall carbon nanotubes (MWNTs) were produced by pyrolysis of ferrocene in a dual furnace system. They grew vertically aligned on oxidized silicon substrates placed inside the reaction zone of a chemical vapor deposition reactor. A variation of the growth parameters has been performed in order to evaluate the possibility to control the Fe-filled nanotube growth process and thereby the nanotube- and the filling length, diameter and yield, and also the nanotube alignment. Electron microscopy studies show nanotubes with quite different morphologies. The relation between the aligned Fe-filled MWNTs growth and the most important growth parameters is discussed. 相似文献
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Effects of Conformal Nanoscale Coatings on Thermal Performance of Vertically Aligned Carbon Nanotubes
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Cinzia Silvestri Michele Riccio René H. Poelma Aleksandar Jovic Bruno Morana Sten Vollebregt Andrea Irace Guo Qi Zhang Pasqualina M. Sarro 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(20)
The high aspect ratio and the porous nature of spatially oriented forest‐like carbon nanotube (CNT) structures represent a unique opportunity to engineer a novel class of nanoscale assemblies. By combining CNTs and conformal coatings, a 3D lightweight scaffold with tailored behavior can be achieved. The effect of nanoscale coatings, aluminum oxide (Al2O3) and nonstoichiometric amorphous silicon carbide (a‐SiC), on the thermal transport efficiency of high aspect ratio vertically aligned CNTs, is reported herein. The thermal performance of the CNT‐based nanostructure strongly depends on the achieved porosity, the coating material and its infiltration within the nanotube network. An unprecedented enhancement in terms of effective thermal conductivity in a‐SiC coated CNTs has been obtained: 181% compared to the as‐grown CNTs and Al2O3 coated CNTs. Furthermore, the integration of coated high aspect ratio CNTs in an epoxy molding compound demonstrates that, next to the required thermal conductivity, the mechanical compliance for thermal interface applications can also be achieved through coating infiltration into foam‐like CNT forests. 相似文献
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Synthesis, Atomic Structures, and Electronic States of Boron Nitride Nanocage Clusters and Nanotubes
Takeo Oku Ichihito Narita Atsushi Nishiwaki 《Materials and Manufacturing Processes》2004,19(6):1215-1239
Boron nitride (BN) nanocage clusters (BnNn: n = 12-60), endohedral BN clusters Y@BnNn, and BN nanotubes were synthesized by an arc-melting method, and characterized by mass spectrometry and high-resolution electron microscopy. The BN clusters consisted of 4-, 6-, 8-, and 10-membered BN rings satisfying the isolated tetragonal rule, which was optimized by molecular orbital calculations. Total energy calculation showed that some elements stabilize and expand the B36N36 structure. Bandgap energies of the B36N36 clusters were found to be reduced by introducing a metal atom inside the cluster, which indicates controllability of the energy gap. Chiralities of BN nanotubes with zigzag- and armchair-type structures were directly determined from high-resolution images, and structure models are proposed. Total energies of BN nanotubes with a zigzag-type structure were lower than those of armchair-type structure, and these results agreed well with the experimental data of disordered tube structure. BN nanotubes encapsulating BN clusters and a yttrium nanowire were also found. This article indicates that the new BN nanocage fullerene materials with various atomic structures and properties can be produced, and a guideline for designing the BN fullerene materials is summarized. 相似文献
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《Fullerenes, Nanotubes and Carbon Nanostructures》2007,15(2):89-97
Arrays of vertically aligned Fe-filled multi-wall carbon nanotubes (MWNTs) on oxidized silicon substrates were prepared by pyrolysis of ferrocene in a dual furnace system and characterized by electron microscopy and magnetometry measurement. The effect of the growth temperature on both the filled nanotube morphology and their magnetic behavior was studied. Increasing the growth temperature in the range of 845-1035°C the nanotube alignment becomes worse and the diameter of the encapsulated Fe nanowires increases from 10 to 40 nm. Both the coercivity and the remanence ratio of the arrays of Fe-filled MWNTs decrease with the increase of the growth temperature. Factors causing the observed magnetic behavior are discussed. 相似文献
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