共查询到20条相似文献,搜索用时 15 毫秒
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以纳米碳管阵列为研究对象,利用镜像悬浮球模型及Fowler-Nordheim电流密度公式,对纳米碳管阵列的场发射电流密度进行计算,进而综合考虑场发射增强因子及场发射电流密度对纳米碳管阵列场发射性能进行定量优化.参考碳管阵列场发射电流密度最大值及场发射增强因子,表明当纳米碳管阵列间距为碳管高度十分之一时,纳米碳管阵列的场发射性能得到优化.与以前的理论估算结果相比,优化的阵列间距进一步减小.当纳米碳管间距过大,场发射增强因子增加,而场发射电流密度会在更大程度上减小;当纳米碳管密度较大时,场发射增强因子受到静电
关键词:
纳米碳管
场发射
增强因子
电流密度 相似文献
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利用场发射显微镜和四极质谱计研究了充入高纯O2的四极质谱和O2对单壁碳纳米管场发射的影响.单壁碳纳米管经过约1000℃的热处理得到清洁态场发射像后,充入O2,分别测量了O2吸附和脱附后场发射的I V特性.实验观测到在单壁碳纳米管上O2的吸附使场发射电流减小,说明逸出功增加.在10-4Pa的O2压强下对单壁碳纳米管进行约1000℃的热处理,可以产生氧化刻蚀作用,观测到场发射像的变化,并测量了氧化刻蚀产生的I V特性变化.
关键词:
单壁碳纳米管
场发射显微镜
场发射
四极质谱 相似文献
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Interference fringes are obtained in a field-emission microscopy
(FEM) study of a multi-walled carbon nanotube (MWCNT) with two
open-ended branches. The FEM pattern, which is composed of three
parallel streaks, can be interpreted by using classical Young's
double-slit interference with the ends of the two MWCNT branches
treated as two secondary sources of the electron wave. The origin of
the coherency of the electron beams from the two branches is
discussed on the basis of the quantitative analysis of the FEM
pattern. The result suggests a new approach to obtaining a coherent
electron source. 相似文献
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Enhanced field emission properties of screen-printed doubled-walled carbon nanotubes by polydimethylsiloxane elastomer 总被引:1,自引:0,他引:1
Field emission (FE) properties of double-walled carbon nanotubes (DWCNTs) treated by polydimethylsiloxane (PDMS) elastomer with different heating temperature have been systematically studied. The current density of treated DWCNT films decreases with the increase of heating temperature. The screen-printed DWCNTs treated by PDMS elastomer with drying temperature 150 °C for 20 min have the best FE performance with a marvelous field enhancement factor (β = 20194). The optimized FE performance is attributed to the morphological change of DWCNT films after PDMS elastomer treatment and the change of separation energy for the CNT-substrate interface. It is proved that the PDMS treatment is a facile and effective method for field emission display (FED) application, especially for low-temperature FED preparation. 相似文献
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研究了Ar离子束轰击及温度对多壁碳纳米管阵列场发射性能的影响.经Ar离子轰击35min后,发现阵列顶端的Fe催化剂颗粒明显减少,弯曲的顶部被轰击掉,使碳纳米管的场发射电流明显减小而场发射像无明显改变.温度的增加引起碳纳米管的场发射电流也随之增加.还研 究了在透明阳极技术中涂在阳极的荧光粉对场发射电流的影响.对同一碳纳米管阵列样品,发现涂有荧光粉的透明阳极使测量到的场发射电流大幅度减小,只是未涂荧光粉阳极电流的 1/30左右.直接用二氧化锡导电膜作阳极时,测得样品的开启场强为1.0V/μm.沉积了荧光粉的二
关键词:
多壁碳纳米管
场发射 相似文献
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对闭口碳纳米管(CNT)顶端分层掺氮及吸附不同数目水分子体系,运用第一性原理研究了有电场存在时的电子场发射性能.结果表明:掺氮并吸附水分子的CNT结构稳定;外电场愈强、水分子数愈多,体系态密度(DOS)向低能端移动幅度愈大且最高分子占据轨道(HOMO)/最低分子空轨道(LUMO)能隙愈小.吸附能,DOS/LDOS,HOMO/LUMO及其能隙分析一致表明,第三层氮掺杂CNT吸附不同数目水分子体系的场发射性能最佳.
关键词:
氮掺杂
水吸附
密度泛函理论
电子场发射 相似文献
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运用密度泛函理论研究了锥顶碳纳米管的结构稳定性与电子场致发射性能.结果表明:在外电场作用下,该体系的结构稳定性明显优于碳纳米锥体、C30半球封口的碳纳米管,且电子发射性能与锥角大小、锥顶构型密切相关,特别是锥角38.9°及棱脊型顶部的cone1@(6,6)综合性能最优,用其作为场致发射源的阴极时可显著提高发射电流密度并延长器件的使用寿命.
关键词:
锥顶碳纳米管
电子场致发射
结构稳定性
密度泛函理论 相似文献
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利用场发射显微镜(FEM)和四极质谱计分别研究了经过热处理的单壁碳纳米管的场发射图像和热处理过程中样品脱附的残气质谱.当热处理温度达到1000℃左右时得到了单壁碳纳米管的场发射像,此像可能是顶端开口的单根(16,0)锯齿形单壁碳纳米管的具有原子可分辨的场发射图像.四极质谱分析结果表明,在此温度范围W针尖晶粒间隙中有O原子和C原子释放出来.它们对单壁碳纳米管顶端的修饰是我们能观察到这些碳纳米管场发射像的可能原因.
关键词:
单壁碳纳米管(SWCNTs)
场发射显微镜(FEM)
四极质谱 相似文献
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Field electron emission microscope images from multi-walled carbon nanotubes can typically be characterized by the presence of five pentagons surrounding a sixth central pentagon. The observations of bright line centered interference patterns between adjacent pentagons in the field electron emission microscope images of multi-walled carbon nanotubes have been reported in the literature. We have observed a shift from bright to dark line centered interference patterns and associated this with the presence of surface adsorption. In order to identify the origin of the contaminant, multi-walled carbon nanotubes were dosed with H2, H2O, CO and O2 and then imaged in the field electron emission microscope. Only the samples exposed to O2 showed a shift from a bright line centered pattern between adjacent pentagons of a clean surface to a dark line centered pattern when one pentagon was contaminated or a bright line centered pattern when both adjacent pentagons become contaminated. The results of the experimental studies and the modeling of the changes in the field emission pattern as phase shifts in the wave function of the tunneling electrons due to modifications in the surface work function are presented. 相似文献
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基于改进的悬浮球模型,计算了碳纳米管和衬底间的接触电阻存在时碳纳米管顶端的局域电场, 并结合Fowler-Nordheim (F-N)场发射规律研究了接触电阻对碳纳米管场发射的影响.研究表明,接触电阻的存在,在高电场区域接触电阻抑制了碳纳米管的电子场发射,导致在高电场区域出现电流饱和及FN直线偏折现象.其原因可归结为接触电阻使得在碳纳米管顶端的局域电场相对于没有接触电阻时相对地减少.
关键词:
碳纳米管
场发射
接触电阻
电流饱和 相似文献
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Field emission properties of capped carbon nanotubes doped by alkali metals:a theoretical investigation 下载免费PDF全文
The electronic structures and field emission properties of capped CNT55 systems with or without alkali metal atom adsorption were systematically investigated by density functional theory calculation.The results indicate that the adsorption of alkali metal on the center site of a CNT tip is energetically favorable.In addition,the adsorption energies increase with the introduction of the electric field.The excessive negative charges on CNT tips make electron emittance much easier and result in a decrease in work function.Furthermore,the inducing effect by positively charged alkali metal atoms can be reasonably considered as the dominant reason for the improvement in field emission properties. 相似文献
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利用化学镀方法对多壁碳纳米管(multi-walled carbon nanotubes,MWNTs)表面金属化镀镍(MWNTs/Ni),采用丝网印刷制备MWNTs/Ni场发射阴极,并在磁场辅助下热处理所得阴极,研究磁场辅助热处理对MWNTs/Ni阴极的场发射性能的影响,经300mT磁场辅助热处理的MWNTs/Ni的场发射阴极开启场强约为0.80V·μm~(-1),场增强因子β约为16068,对单根MWNTs/Ni在磁场中的受力情况进行建模分析,实验结果表明:磁场辅助热处理有助于提高MWNTs/Ni在阴极表面的直立分布,提高了MWNTs/Ni的场发射性能。 相似文献
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Electron emission properties of single-walled carbon nanotubes (SWCNTs) assembled on a tungsten tip were investigated using field emission microscopy (FEM). The transmission electron microscopy (TEM) micrograph confirmed the existence of an SWCNT bundle on the W tip. Under appropriate experimental conditions,a series of FEM patterns with atomic resolution were obtained. These patterns arose possibly from the field emission of the open end of an individual (16,0) SWCNT protruding from the SWCNT bundle. The magnification factor and the resolution under our experimental conditions were calculated theoretically. If the value of the compression factor β was set at β= 1.76, the calculated value of the magnification factor was in agreement with the measured value. The resolving powerof FEM was determined by the resolution equation given by Gomer. The resolutionof 0.277 nm could be achieved under the typical electric field of 5.0×107 V/cm, which was close to the interatomic separation 0.246 nm between carbon atoms along the zigzag edge at the open end for the (16, 0) SWCNT. Consequently, our experimental results were further supported by our theoretical calculation. 相似文献