Ni基碳纳米管场发射阴极的性能研究

导电电极决定碳纳米管（CNT）阴极的接触方式和导电特性,影响阴极场发射特性和使用寿命.为改善膜层与基底的附着特性,磁控溅射制作亲碳性Ni电极.微观表征发现Ni基CNT阴极中生成了碳化镍相,这增加了CNT与电极间形成欧姆接触概率,降低甚至消除了从电极到CNT的电子传输势垒,能有效提高阴极导电性.场发射特性测试结果显示Ni...     

电泳和电镀法增强碳纳米管场发射特性的研究

碳纳米管(CNT)和衬底的电学接触问题是获得高性能CNT电子器件的一个关键性的问题。本文采用电泳电镀方法制备CNT冷阴极,有效改善了CNT与衬底间接触电阻,增强了碳纳米管场发射性能。电泳电镀法制备的碳纳米管冷阴极场发射的开启电场(电流密度为10μA.cm-2时的电场)由2.95 V.μm-1降低到1.0V.μm-1,在电场为8V.μm-1时电流密度由0.224增加到0.8112mA.cm-2。在电流密度为800μA.cm-2时进行1h的场发射稳定性测试,结果表明,电泳电镀法所得CNT场发射电子源电流密度几乎不变,而且电流密度比较稳定;而只有电泳的方法获得的CNT场发射电子源电流密度波动较大,电流不稳定且呈较快的衰减趋势,1h后减少到原来的75%。采用电泳电镀方法制备CNT阴极,CNT的根部被纳米银颗粒覆盖和包裹,使CNT与衬底接触更加牢固而紧密,又由于银具有很好的导电性,从而大大减小了接触电阻,因此电泳电镀法能大大改善CNT与衬底的电学接触性能。     

碳纳米管阵列研究进展

在介绍CNT阵列性能的基础上,对国内外直接合成CNT阵列的方法进行了评述,重点阐述了各种方法的基本特点及CNT阵列的生长机理、结构控制和批量制备问题。进而探讨了CNT原生阵列、抽丝形成的CNT丝、以及CNT阵列分散后得到的CNTs在复合材料、力学增强、功能器件等方面的初步应用,展望了CNT阵列的发展趋势,指出低成本、大批量可控制备CNT阵列仍然是未来一段时间内国际研究热点。     

硝磷酸腐蚀的CdTe太阳电池性能

CdTe薄膜的腐蚀是制作CdS/CdTe光伏电池的重要技术之一,本实验采用硝磷酸溶液（硝酸1%＋磷酸70%＋去离子水29%）腐蚀CdTe薄膜,通过XRD测试发现在CdTe膜上生成了碲层.随后,在腐蚀后的CdTe薄膜上分别沉积了几种结构的背接触层,并制备出相应结构的CdTe太阳能光伏电池.通过电池的光、暗I-V和C-V特性测试,以ZnTe/ZnTe：Cu/Ni为背接触的小面积太阳电池,其性能优于其它背接触的电池.实验结果表明器件性能与碲的生成和铜的扩散密切相关.     

基于原子力显微镜的碳纳米管焊接

在利用碳纳米管（CNT）制作纳米电子器件时,碳纳米管与金属电极的接触特性将决定器件性能.为此本文提出了一种利用原子力显微镜（AFM）进行碳纳米管焊接的新方法.仿真研究了探针电场的强度与分布,解释了焊接中电场产生的机理,进一步分析了偏压、探针-样品距离与探针悬臂梁偏转位移之间的关系;并通过这些优选的相关实验参数进行了焊接实验验证.实验结果表明,碳纳米管与电极间的接触电阻由2.86×106Ω减小至7.14×105Ω,并可实现碳纳米管在电极上的良好固定.     

紫外-可见光谱分析碳纳米管电泳液浓度对阴极场发射性能的影响

将酸化的碳纳米管(CNT)粉末、硝酸镁置于异丙醇溶剂中超声处理,制备成分散均匀的CNT电泳液.采用不同CNT浓度的电泳液在CrCuCr电极上电泳沉积CNT薄膜,并对阴极样品进行场发射性能测试;同时采用紫外-可见光谱仪对CNT电泳液进行光谱分析.结果表明,CNT浓度为0~0.13 g/L的电泳液在258 nm处存在光谱吸收,且其吸光度与相应CNT浓度呈良好的线性关系;当CNT浓度为0.12 g/L时电泳沉积制备的CNT阴极场发射性能较好,其开启电场为0.903 V/μm,当电场强度为1.395 V/μm时场发射电流密度为2.903 mA/cm2.利用紫外-可见光谱可以有效地分析电泳液中CNT浓度,为电泳沉积良好质量的CNT薄膜提供了保证.     

不同沉积工艺下Au/P-CdZnTe接触界面的研究

采用超声波扫描(SAM)、俄歇电子能谱分析技术(AES)、电极粘附力测试和I-V特性测试等方法研究了化学沉积、溅射和真空蒸发三种不同沉积工艺条件下Au/p-CdZnTe接触界面的各种特性.通过实验结果可以看出,化学法沉积的Au电极能形成较好的欧姆接触特性,但其操作工艺不容易控制,电极接触层均匀性较差,在器件使用过程中,容易引起电极的退化;溅射沉积的Au电极有着较好的附着力,但对CdZnTe表面的损伤较大,欧姆接触特性较差;真空蒸发法沉积的Au电极,有着较好的欧姆接触特性,且其电极接触层也较为均匀,只是电极附着力相对较小,但可以通过合适的退火工艺进行改善.     

压电集成碳纳米管CNT增强功能梯度结构非线性建模与仿真

将碳纳米管(carbon nanotube,CNT)以梯度形式分布与基体材料结合,形成功能梯度(functionally graded,FG)结构。为了实现FG-CNT增强复合板在发生大变形时的准确计算,考虑四种典型的CNT分布形式,均匀分布、V型分布、O型分布和X型分布,建立基于Reissner-Mindlin板壳假设的大变形几何非线性有限元模型。该模型不仅包含了几何全非线性应变位移关系,还考虑了薄板结构法向发生大转角的情形。该研究与文献结果进行比较,验证模型的准确性;对FG-CNT增强复合板进行几何大变形非线性计算,分析CNT分布形式、CNT增强角度等因素对FG-CNT增强复合板刚度的影响。研究结果表明,CNT分布形式及增强角度对FG-CNT复合板的力学特征有显著的影响。     

碳纳米管/聚合物复合材料界面结合性能的研究进展

碳纳米管(CNT)优异的力学性能使其成为复合材料优选的增强体。CNT/聚合物复合材料的力学性能主要受其界面结合性能的影响。综述了CNT/聚合物复合材料界面结合性能的研究方法和研究现状。对CNT/聚合物复合材料界面结合性能的研究,实验上采用微观表征技术、拉曼光谱分析技术和纳米力学拔出法,分子模拟方法则是通过对CNT施加位移或外力模拟CNT从聚合物基体中的抽拔过程。概述了聚合物的类型、晶态结构以及CNT的手性、功能化处理等因素对CNT/聚合物复合材料界面结合性能的影响,并展望了CNT/聚合物复合材料界面结合性能未来研究的重点方向。     

碳纳米管/聚苯乙炔复合材料的导电性

用AlCl₃ 作催化剂制备了聚苯乙炔( PPA) , 用浓H₂SO₄ 进行磺化改性, 通过共混制得碳纳米管(CNT) /PPA 及磺化CNT/ PPA 复合材料, 进行导电性能、XRD 等测试。当CNT 含量增加时, 复合材料的电导率升高, 磺化CNT/ PPA 的导电阈值比CNT/ PPA 的导电阀值降低了1 %, 前者达到极限电导率所需CNT 的量是后者的10 %; 分析了随着温度变化影响复合材料电阻变化的因素; XRD 测试表明, 在CNT 界面上的磺化PPA 有新的晶型产生。      

Nanoinfiltration behavior of carbon nanotube based nanocomposites with enhanced mechanical and electrical properties

In this work,carbon nanotube (CNT) based nanocomposites with high mass fraction are proposed by in-situ bridging carbon matrix into CNT paper through optimized chemical vapor infiltration (CVI).Nanoinfiltration behavior of CNTs is basically investigated under the CVI process.The contact between each CNT can be strengthened and the conductive pathways can be established,resulting in the better mechanical and electrical properties.Compared with the pristine CNT paper,the CNT/C composite after pyrolysis process confirms a remarkable advance in tensile strength (up to 310 ± 13 MPa) and Young's modulus (up to 2.4 ± 0.1 GPa).Besides,a notable feature of electrical conductivity also shows an improvement up to 8.5 S/cm,which can be attributed to the mass fraction of CNT (41 wt％) breaking the limits of percolation thresholds and the efficient densification of this sample to establish the conductive pathways.This study has a broad application in the development of the multi-functional electrical and engineering materials.     

碳纳米管复合材料场发射性能研究现状

碳纳米管具有管径小、长径比高的结构以及物理化学性能稳定等优良特性,被认为是真空冷阴极场发射电子源和场发射平板显示理想的阴极材料。加之碳纳米管兼具有机械强度高、韧性好等出众的力学性能,使其成为复合材料的理想添加相,将其与其他材料复合,可以制备出具有更加出众性能的复合材料。近年来有关碳纳米管及其复合材料场发射研究已成为一个备受关注的热点。概述了阴极场发射理论以及与碳纳米管场发射相关的几种场发射物理机制,介绍了碳纳米管复合场发射阴极的研究现状及制备方法,最后对碳纳米管复合阴极场发射的发展前景进行了展望。     

Achieving Good Strength–Plasticity Compatibility in Cu Composites via Carbon Nanotube-Induced Heterogeneous Bimodal Structure

Traditionally, metal matrix composites reinforced with uniformly dispersed carbon nanotube (CNT) have shown significant enhancement in strength, but always accompanied by the deterioration of uniform elongation (UE). Herein, a novel strategy is proposed to achieve the prominent strength–ductility combination of CNT-reinforced Cu composites. The strategy makes use of the architecture design via mixing the CNT/Cu composite powders (prepared by the molecular-level mixing method) with coarse-grained Cu powders. The bulk composites with a controlled inhomogeneous microstructure are designed and fabricated, in which the reinforcing phase is inhomogeneously distributed at the microscale but homogeneous at the macroscale. The effects of fine and coarse grain proportions on the microstructure evolution and plastic deformation capacity of bimodal-grained Cu composites are investigated. When the mixed ratio of refined CNT/Cu powder to coarse-grained Cu is 1:1, the ultimate tensile strength (UTS) and UE of bimodal-grained Cu composites are 384 MPa and 26.9%, respectively. Such good strength–plasticity compatibility is attributed to the combined effects of hetero-deformation-induced (HDI) stress and CNT strengthening mechanisms. This study provides insights for evading the strength–ductility trade-off in high-performance metal matrix composite by architecture design.     

Carbon nanotube dispersion in aluminum matrix composites—Quantification and influence on strength

Carbon nanotube (CNT) incorporation in metal matrix composites is hampered by the development of attractive van der Waals forces, which lead to the formation of CNT agglomerates. Therefore, a detailed quantification and characterization of CNT agglomerates and consequently CNT dispersion can enlighten their influence in composites strength. This work presents a comprehensive study, quantifying agglomerates by size, for three different composites (2, 4, and 6 CNT vol%), made with an aluminum-silicon matrix by a powder metallurgy route. From the obtained experimental data, an empirical model that attempts to predict the tensile strength of these composites from CNT agglomerates analysis is presented.     

流体组装制造的金属-碳纳米管-金属结构

基于碳纳米管的纳米器件制造中,金属-碳纳米管-金属结构是重要部分通过流体组装多壁碳纳米管,并在其上沉积、光刻图形化金属制造了金属-碳纳米管-金属结构．对比不同流体组装条件下的排列效果发现,较大的样品台倾角和较高的气流速度可实现较好的碳纳米管组装．通过对碳纳米管与金属间的接触电阻进行估算和比较,金属包覆碳纳米管比碳纳米管沉积在全电极上的接触方式具有更小的接触电阻和接触电阻分散性,且碳纳米管与金电极接触状态比钛电极好最终通过该方法制造出了接触良好的金属-碳纳米管-金属结构。     

纸基碳纳米管薄膜/叉指结构的超灵敏宽量程压力传感器（英文）

柔性压力传感器因其在可穿戴设备和人机交互界面中的潜在应用而备受关注.特别是在实际应用中,人们对具有高灵敏度、宽测量范围和低成本的压力传感器有很大需求.基于此,我们研制出了一种测量范围宽的超灵敏压力传感器.该传感器是以碳纳米管(CNT)均匀溶液直接喷在纸表面作为敏感材料,用光刻技术制成的叉指电极为结构.由于CNT大的比表面积、纸的多孔结构以及CNT与叉指电极有效接触的协同作用,压力传感器实现了从0到140 kPa的宽测量范围,并在15,000个测试周期内表现出良好的稳定性.对于纸基碳纳米管薄膜/叉指状结构(PCI)压力传感器,敏感材料与叉指电极之间的连接区域在较小的压力范围内占主导地位,而敏感材料的内部变化在大的压力区域起主导作用.此外PCI压力传感器不仅具有2.72 kPa-1(直到35 kPa)的高灵敏度,还可以检测小重量,如一颗绿豆(约8 Pa).当压力传感器贴附到人体表面时,可以监测生理信号,如手腕运动、脉搏跳动和语音识别.此外,压力传感器的阵列能够识别空间压力分布,有望实际应用于人机交互界面.     

Binder-free activated carbon/carbon nanotube paper electrodes for use in supercapacitors

Novel inexpensive, light, flexible, and even rollup or wearable devices are required for multi-functional portable electronics and developing new versatile and flexible electrode materials as alternatives to the materials used in contemporary batteries and supercapacitors is a key challenge. Here, binder-free activated carbon (AC)/carbon nanotube (CNT) paper electrodes for use in advanced supercapacitors have been fabricated based on low-cost, industrial-grade aligned CNTs. By a two-step shearing strategy, aligned CNTs were dispersed into individual long CNTs, and then 90 wt%–99 wt% of AC powder was incorporated into the CNT pulp and the AC/CNT paper electrode was fabricated by deposition on a filter. The specific capacity, rate performance, and power density of the AC/CNT paper electrode were better than the corresponding values for an AC/acetylene black electrode. The capacity reached a maximum value of 267.6 F/g with a CNT loading of 5 wt%, and the energy density and power density were 22.5 W·h/kg and 7.3 kW/kg at a high current density of 20 A/g. The AC/CNT paper electrode also showed a good cycle performance, with 97.5% of the original capacity retained after 5000 cycles at a scan rate of 200 mV/s. This method affords not only a promising paper-like nanocomposite for use in low-cost and flexible supercapacitors, but also a general way of fabricating multi-functional paper-like CNT-based nanocomposites for use in devices such as flexible lithium ion batteries and solar cells.      

A General Method for the Chemical Synthesis of Large‐Scale,Seamless Transition Metal Dichalcogenide Electronics

The capability to directly build atomically thin transition metal dichalcogenide (TMD) devices by chemical synthesis offers important opportunities to achieve large‐scale electronics and optoelectronics with seamless interfaces. Here, a general approach for the chemical synthesis of a variety of TMD (e.g., MoS₂, WS₂, and MoSe₂) device arrays over large areas is reported. During chemical vapor deposition, semiconducting TMD channels and metallic TMD/carbon nanotube (CNT) hybrid electrodes are simultaneously formed on CNT‐patterned substrate, and then coalesce into seamless devices. Chemically synthesized TMD devices exhibit attractive electrical and mechanical properties. It is demonstrated that chemically synthesized MoS₂–MoS₂/CNT devices have Ohmic contacts between MoS₂/CNT hybrid electrodes and MoS₂ channels. In addition, MoS₂–MoS₂/CNT devices show greatly enhanced mechanical stability and photoresponsivity compared with conventional gold‐contacted devices, which makes them suitable for flexible optoelectronics. Accordingly, a highly flexible pixel array based on chemically synthesized MoS₂–MoS₂/CNT photodetectors is applied for image sensing.     

碳纳米管增强金属基复合材料的研究进展

碳纳米管增强金属基复合材料由于高的比强度、比模量以及优异的热、电性能在航空航天领域具有很好的应用潜力,本文在分析大量文献的基础上,评述该类材料的制备技术和界面研究进展,对其典型性能进行归纳,指出碳纳米管的分散技术以及碳管、基体之间的界面特性应该是今后本领域的重点研究方向。