共查询到15条相似文献,搜索用时 46 毫秒
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一种新的纳米结构--管状石墨锥 总被引:1,自引:0,他引:1
文章作者利用微波等离子体辅助化学气相沉积的方法在铁针尖上合成了一种新的纳米结构,并称之为管状石墨锥.管状石墨锥在外形上由多面锥体组成,其内部是同心的圆柱形石墨层,其空心的直径为几个纳米到几十个纳米.这些管状石墨层从内到外地逐渐变短,从而使得它们呈现出锥形外观.锥的顶角一般为6-7度左右,锥的尖端只有几个纳米大小,而锥的底部可达到微米量级.值得注意的是,组成管状锥体的石墨层具有惟一的手性,都表现为锯齿型。 相似文献
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一种新的制备ZnO纳米粒子的方法--阴极电沉积法 总被引:6,自引:2,他引:6
用阴极电沉积法制备高质量ZnO纳米薄膜,电沉积采用含有不同浓度的ZnCl2的非水二甲基亚砜溶液做电解液,室温下恒流沉积,得到纳米ZnO薄膜。研究了ZnCl2浓度对薄膜结构和光学性质的影响。沉积薄膜的ZnO粒径尺寸分别为9.8,10.4,14.5nm。随着ZnCl2浓度的增加而增大。薄膜的可见光致发光谱以紫外的自由激子发射为主。研究表明:以浓度为0.03mol/L的ZnCl2电解液制备的ZnO薄膜光学性质最好。 相似文献
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利用扫描力显微术的压电响应模式,并基于逆压电效应原理,研究了梯度组成的PZT铁电薄膜纳米尺度铁电畴的场致位移特性.获得了源于纳米尺度铁电畴的压电效应和电致伸缩效应贡献的场致位移回滞线,以及源于线性压电效应和电畴反转效应综合贡献的纳米尺度压电位移 场强蝶形曲线,证实了Caspari Merz理论在纳米尺度上的有效性.发现了梯度铁电薄膜存在纳米尺度印刻现象,认为该现象的内因源于薄膜中的内偏场.
关键词:
PZT铁电薄膜
场致位移
纳米尺度
扫描力显微术 相似文献
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一种基于三氟甲基取代的2-苯并[b]噻吩基吡啶配体的红色电致磷光材料及器件 总被引:2,自引:1,他引:1
研究了一种新型红色磷光材料及其在有机电致磷光器件(OLEDs)中应用.在经典红色磷光材料btp2Ir(acac)的配体2-苯并噻吩吡啶的吡啶环的5位引入吸电子基团CF3,将辅助配体换为2-吡啶甲酸,成功研制出了双(2-(2′-苯并[b]噻吩基)吡啶)吡啶甲酸合铱配合物[(btfmp)2Ir(pic)].这种结构可以改变了原配合物的电子云分布,三氟甲基的引入将导致原分子的LUMO能下降,减小了HOMO与LUMO的能隙,引起发光峰位的红移,但2-吡啶甲酸又可引起发光蓝移,最终得到了最大峰位为637nm的饱和红光新的铱(Ⅲ)配合物,为通过简单配体修饰设计和制备新的有机磷光材料提供了一种简洁途径. 相似文献
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以二茂铁、二甲苯为前驱体,石英为衬底,在850 oC的管式炉内采用化学气相沉积法制备出了定向碳纳米管阵列. 高分辨透射电子显微镜和拉曼光谱的结果表明:碳纳米管阵列具有良好的定向性和多壁管状结构,石墨化程度高,并且只在表面存在少量单壁碳纳米管.定向多壁碳纳米管阵列的生长模式为“底部”生长模式,即在生长的初期,当催化剂颗粒较小时,析出的碳原子生成了单壁碳纳米管或与其性质类似的多壁碳纳米管(一般层数小于5层);催化剂颗粒逐渐长大后,大量的碳原子析出后生成了普通的多壁碳纳米管,从而形成了单壁碳纳米管只存在于碳纳米管阵列膜表面和多层碳纳米管膜表面与界面的现象. 相似文献
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Martina Hribova Frantisek Rybnikar Jarmila Vilcakova 《Journal of Macromolecular Science: Physics》2013,52(1):16-25
Microscopical, differential scanning colorimetry (DSC), and X-ray structural investigations of solution crystallized carbon nanotube (CNT) composites with linear polyethylene (LPE), isotactic polypropylene (iPP), polybutene-1 (PB-1), and nylon 6 (PA6) disclosed varying degrees of surface interaction and nucleation effect of CNT in these polymers and formation of oriented shish-kebab overgrowths on the CNT ropes in LPE and PA6. The character of the attraction and orientation forces at the CNT-polymer interface is discussed. 相似文献
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碳纳米管场发射显示器的研究进展 总被引:8,自引:6,他引:8
碳纳米管因具有良好的电子发射特性而成为理想的场发射阴极材料,利用碳纳米管作阴极的场致发射平板显示器件的研究是目前显示技术领域的研究热点之一。报道了场发射显示器(FED)的结构及工作原理、阴极发射材料应具有的特点及碳纳米管在场发射领域中的应用情况。详细地论述了碳纳米管的场致发射特性,包括开启电场、发射电流密度、电流稳定性及发射点密度等,对国内外碳纳米管场发射显示器的发展现状及趋势作了回顾和展望,并对目前所面临的主要问题作了分析,同时提出了一些改进的思路。 相似文献
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钾掺杂多壁纳米碳管储氢性能研究 总被引:3,自引:0,他引:3
使用自制的钴催化裂解碳氢气法制备多壁纳米碳管 ,并对其进行退火、掺杂等一系列预处理 ,然后使用高压高纯氢源 ,在中压 (12MPa)和室温条件下 ,进行钾掺杂多壁纳米碳管的储氢性能实验 .结果表明 :预处理对纳米碳管的储氢性能有很大影响 .实验条件下 ,经过氮气退火 ,并在 1.0mol/L硝酸钾溶液中掺杂的多壁纳米碳管吸氢量最大 (H/C质量分数为 3.2 % ) .上述样品在室温下的放氢量一般不超过其吸氢量的 5 0 .8% . 相似文献
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Sun-Kuk Kim Jeong Tai Kim Hee-Cheul Kim Kyong-Yop Rhee John Kathi 《Journal of Macromolecular Science: Physics》2013,52(2):358-367
Multi-scale hybrid composite laminates of epoxy/carbon fiber (CF) reinforced with multi-walled carbon nanotubes (MWCNTs) were fabricated in an autoclave. For laminate fabrication, 0.5 wt% of pristine MWCNTs or silane-functionalized MWNCTs (f-MWCNTs) were dispersed into a diglycidyl ether of bisphenol-A epoxy system and applied on the woven carbon fabric. The neat epoxy/CF composite and the MWCNTs-reinforced epoxy/CF hybrid composites were characterized by thermogravimetric analysis (TGA), thermomechanical analysis (TMA), tensile testing, and field emission scanning electron microscopy (FE-SEM). A significant improvement in initial decomposition temperature and glass transition temperature of epoxy/CF composite was observed when reinforced with 0.5 wt% of f-MWCNTs. The coefficient of thermal expansion (CTE), measured by TMA, diminished by 22% compared to the epoxy/CF composite, indicating an improvement in dimensional stability of the hybrid composite. No significant improvement in tensile properties of either MWCNTs/epoxy/CF composites was observed compared to those of the neat epoxy/CF composite. 相似文献
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Theoretical calculations have predicted that individual Single-Walled Carbon Nanotubes (SWNT) have extremely high thermal
conductivity (around 6.6 × 104 W/m-K). The feasibility of constructing practical devices using the above mentioned properties, is critically dependent on
the ability to synthesize high-thermal-conducting films. Highly conducting films would be of great use as heat sinks for the
next generation of integrated chips. Excessive heating is currently a very serious problem in the endeavor for achieving faster
and smaller chips. Since it is still not possible to perfectly align SWNT in the macroscopic scale, the thermal properties
of the nano-films are therefore expected to have a statistical effect and thus lower than the intrinsic thermal conductivity
of a single nanotube. Also the thermal conductivity perpendicular to the tube direction is more significant from a practical
point of view. Multi-Walled Carbon Nanotubes (MWNT) were synthesized by Chemical Vapor Deposition (CVD) technique and subsequently
characterized. The thin MWNT films were deposited by a solution casting technique over a metallic substrate. The off-axis
thermal properties of these nano-films were studied by AC-calorimetry studies. In this method, the sample is heated by an
AC source and the measurement of the relaxation rate is used to determine the thermal properties. This technique is well established
for studying the thermal properties of complex fluids. Our results are contrasted with other thermal conductivity measurements
intrinsic and bulk carbon nanotube samples. We have also measured off-axis thermal properties of nano-films synthesized from
more crystalline SWNT samples and have compared this result with that of the MWNT-film. A model to explain the thermal conduction
for our system is proposed.
George Muench: Presently at the Department of Physics, University of New Haven, West Haven, CT-06516, USA 相似文献
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关于碳纳米管反常反斯托克斯拉曼(AASR)光谱现象的研究 总被引:1,自引:1,他引:0
在碳纳米管中观察到了反常反斯托克斯拉曼(AASR)光谱现象,并发现AASR现象与碳纳米管的管层数和碳材料的片层样结构无关,因而揣测它可能只与碳纳米管的管状结构有联系。 相似文献