Ni颗粒对碳纳米管场致电子发射的影响

根据Fowler-Nordheim的场致电子发射机制建立了顶端被催化剂Ni颗粒封闭的碳纳米管场致电子发射模型.利用该模型分析了Ni颗粒被移去前后碳纳米管场致电子发射性能的差异.分析结果表明Ni颗粒被移去前后碳纳米管场致电子发射性能的差异主要起源于碳纳米管顶端处电场强度的不同.     

高亮度碳纳米管背光源的制备及特性研究

利用酸化及球磨工艺对碳纳米管(Carbon Nanotubes,CNTs)进行表面改性及分散处理,通过丝网印刷技术制备碳纳米管阴极并真空封装碳纳米管背光源原型器件.透射电镜(TEM)及扫描电镜(SEM)分析表明,酸化及球磨处理后的碳纳米管表面产生管壁缺陷并分散均匀,有利于改善碳纳米管场发射性能.通过器件性能测试,亮度高达到5 000 cd·m-2,稳定发射35 h,发射电流无明显衰减.     

优化催化剂密度改善碳纳米管薄膜纯度与场发射特性

对涂敷有不同浓度催化剂的硅基生长出的碳纳米管薄膜的生长状况和特性进行了研究，并且获得了催化剂的优化浓度，在基底上涂敷氢氧化铁溶胶从而引入催化剂颗粒，用低压化学气相沉积法生长出碳纳米管薄膜，工艺表明，碳纳米管薄膜的生长状况受到催化剂密度的影响，当密度太高时，碳纳米管薄膜的尖端效应不明显，且杂质含量较高；当密度太低时，无法生长出均匀的碳纳米管薄膜，扫描电镜分析和场发射特性测试表明，涂敷有优化浓度的催化剂生长出的碳纳米管薄膜，具有更明显的尖端效应，更高的纯度，阈值电压降到95V，透射电镜观察到的碳纳米管直径为10-100nm。     

掺氮碳纳米管阵列的制备及其场发射特性

使用结构简单的单温炉设备,以二茂铁为碳源与催化剂,三聚氰胺为氮源在硅基底制备出了碳纳米管阵列。所得的碳纳米管为多壁结构,单根碳纳米管的平均直径为50nm,长度为15μm,有着很好的定向性。透射电子显微镜(TEM)和X射线光电子谱(XPS)分析表明所得的碳纳米管是氮掺杂的。利用场发射显微镜研究了掺氮碳纳米管阵列的平面场发射特性,相应的开启场强为1.60V/μm,场发射图像表明了其有较高的场发射点密度。     

单根碳纳米管的低温电输运性质

报道了单根碳纳米管的低温电输运测量结果,特别关注了由于碳纳米管在长度方向的尺寸较小时产生的库仑阻塞性质,碳纳米管的低温电输运出现了零偏置反常和库仑振荡。因此碳纳米管在小的尺寸和低温时不仅出现能量量子化而且可以出现电荷量子化-量子点的行为。     

镍基纳米碳管薄膜冷阴极场致发射特性及失效行为

对镍基纳米碳管薄膜冷阴极场致发射特性进行了多次反复的测量,发现了该材料在特定条件下会发生失效行为,并对此现象进行了初步的分析.     

多壁碳纳米管薄膜场发射规律实验研究

研究了CVD法定向生长的多壁碳纳米管薄膜的在高电压条件下场发射特性 .我们发现在固定电压条件下发射电流和时间的关系按指数规律减弱 .另一个值得关注的现象是碳纳米管的发射性能的不可恢复性损坏 .电流电压关系也由幂次关系I =aVb 改变为幂次关系I =a(V -V0 ) b′,其中 ,b和b′的值均为 2～ 3.最后讨论了电流减弱的原因     

Field electron emission of diamond films on nanocrystalline diamond coating by CVD method

Generally, nucleation and growth of diamond were difficult on substrates without being pretreated when diamond films were prepared with the chemical vapor deposition (CVD) method. To improve nucleation, two methods were adopted; one is mechanically treating sur-faces of substrates with superhard particles, the other is introducing substrate bias to the substrates. However, these two processes were difficult to bring about industri-alization owing to their complicated procedures and the diffic…     

Influence of deposition time on the morphology and optical properties of SiO<Subscript>2</Subscript>-ZnO composite photonic crystals

SiO2 photonic crystal were successfully prepared by vertical deposition and then used as a template to fabricate SiO2-ZnO composite photonic crystals on ITO substrates by electrodeposition and subsequent calcination. A number of different deposition times were used. The morphologies of the silica opals and SiO2-ZnO composite photonic crystals were investigated by scanning electron microscopy. It was found that ZnO particles grew randomly on the surfaces of the silica spheres when the deposition time was short. As the deposition time was increased, the ZnO particles grew evenly on the surfaces of the silica spheres so that the interstitial space of the silica template was filled with ZnO particles. Reflectance spectra of the SiO2-ZnO composite crystals revealed that all of the fabricated photonic crystals exhibit a photonic band gap in the normal direction.     

氮掺杂碳化硅纳米管电子场发射的第一性原理研究

运用第一性原理研究了氮掺杂对碳化硅纳米管场发射性能影响.计算结果表明,在外加电场作用下,体系的态密度均向低能端移动,赝能隙及最高占据分子轨道/最低未占据分子轨道能隙减小,且Mulliken电荷在帽端聚集程度增加.态密度、最高占据分子轨道/最低未占据分子轨道能隙及Mulliken电荷分析表明,氮掺杂改善了碳化硅纳米管的场发射性能,且N替代顶层五元环中Si原子体系场发射性能最优.     

碳纳米管场发射显示屏栅极工艺的研究

利用优质云母板作为栅极结构基底材料，结合简单的丝网印刷工艺将导电银浆制作成条状栅极，制作了新型的栅极结构；采用高温分解方法制备了碳纳米管薄膜阴极，制作了三极结构碳纳米管阴极平板显示屏样品。该样品具有良好的场致发射特性以及栅极控制能力。利用这种新型的栅极结构，能够克服整体器件高温封装所带来的技术困难，避免碳纳米管阴极和阳极荧光粉的损伤，实现了稳定可靠的高温封装，具备了制作大面积场致发射器件的潜力。     

Catalytic self-assembly preparation and characterization of carbon nitride nano-tubes by a solvothermal method

A solvothermal reaction of anhydrous CaNaCl3 and sodium using cyclohexane as solvent and NiCI2 as catalyst precursor has been carried out to prepare carbon nitride nanotubes successfully at 230℃ and 1.8 MPa. The carbon nitride nanotubes were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron diffraction (ED), electron energy loss spectrum (EELS) and Raman spectrum.SEM and TEM results indicated that the tubes have a length of 20-30 μm, a uniform outer diameter of about 50-60 nm,an inner diameter of 30-40 nm and are highly ordered assembled as bundles. The EELS measurement indicated that the ratio of N/C was about 1.00. The ED and XRD analyses revealed that the tube may have a new CN crystalline structure. The growth mechanism of nanotubes was discussed.     

不锈钢衬底碳纳米管薄膜的场发射特性

不需要添加任何催化剂,直接在含有少量Ni和Cr成分的不锈钢衬底上,用微波等离子体化学气相沉积(MPCVD)方法沉积碳纳米管薄膜.在SEM下观察,生成的碳纳米管取向无序,但浓度大、杂质含量少、直径小且分布均匀,其直径在50～60 nm,为多壁碳纳米管.Raman光谱实验证实了此碳纳米管中存在大量缺陷.场发射实验表明,本样品的开启电压低,电子发射均匀,发射电流大.当用ITO玻璃作阳极且场强为11 V/μm时,电流密度可达到31 mA/cm2;当用荧光粉包覆的ITO玻璃作阳极且场强为6 V/μm时,电流密度可达到1.25 mA/cm2,这时的电子可稳定发射,使该样品变成良好的电子发射体.     

碳纳米管应用研究的现状和未来

综述了碳纳米管的潜在应用前景，并提出随着碳纳米管合成技术的成熟，有关碳纳米管的研究重点应转向大批量生产碳纳米管及其应用领域的开拓上。     

Deposition of the platinum crystals on the carbon nanotubes

A new technique and the affecting factors for depositing platinum on the carbon nanotubes were investigated. The results show that the deposited platinum crystals in the atmosphere of hydrogen or nitrogen have a small size and a homogeneous distribution on the surface of the carbon nanotubes. The pretreatment would decrease the platinum particles on the carbon nanotubes significantly.     

Electron field emission from nano-crystalline Si films deposited by inductively coupled plasma CVD at room temperature

ELECTRON FIELD EMISSION IS ONE OF THE INTERESTING PER- FORMANCES OF NANO-SCALE MATERIALS [1-3]. CARBON NANO- TUBES HAVE BEEN DEMONSTRATED TO BE THE MOST FASCINAT- ING MATERIAL OF ELECTRON FIELD EMISSION, BUT THEIR INSTA- BILITY OF EMISSION DUE TO THE AGING EFFECT LIMITS THEIR APPLICATION IN VACUUM ELECTRONICS [4]. SI TIPS HAVE MORE FAVORITE GEOMETRIC FEATURE AND MORE STABLE C…     

用机械破碎方法提高印刷碳纳米管薄膜的场发射性能

提出了一种可显著改善丝网印刷碳纳米管(CNTs)薄膜场发射特性的后处理方法,用机械压力通过隔离层对附着于CNTs表面的无机物进行原位破碎,并用高速气流清洁薄膜表面.同其他方法相比,机械破碎方法既不会在处理后的阴极表面留下残留物,也不会使薄膜受损.场发射特性测试表明,与未处理薄膜相比,经过处理的CNTs薄膜的开启场强从2.7V/μm降低到1.7V/μm,同样面积的薄膜(印刷面积为40mm×40mm)在4.2V/μm场强下的发射电流由70μA提高到了950μA,说明机械破碎处理对于提高薄膜的场发射特性有明显作用.该方法在碳纳米管场发射显示器的制作中具有很好的实际应用价值.     

First-principles study of the effects of Si doping on geometric and electronic structure of closed carbon nanotube

The effects of Si doping on geometric and electronic structure of closed carbon nanotube （CNT） are studied by, a first-principles method, DMol. It is found that the local density of states at the Fermi level （Er） increases due to the Si-doping and the non-occupied states above the Er go down toward the lower energy range under an external electronic field. In addition, due to the doping of Si, a sub-tip on the CNT cap is formed, which consisted of the Si atom and its neighbor C atoms. From these results it is concluded that Si-doping is beneficial to the CNT field emission properties.     

调频场作用下双光子电离光电子谱特性

应用微扰理论和数值计算方法,研究了调频光场作用下激发与电离模型中双光子电离光电子谱的相干特性.分析了调频光场的调制振幅、调制频率以及初相位对双光子电离光电子谱的影响.结果表明,调制振幅、调制频率以及初相位对双光子电离光电子谱有调制作用.选取合适的参量,可以实现对双光子电离光电子谱的量子控制.这一相干量子控制的机理是强场作用下激发态的粒子在两个缀饰态之间的选择性布局所致.