含钪扩散阴极电子发射研究

采用水冷阳极平板二极管结构测试了含钪扩散阴极，结果表明，它有比其它扩散阴极更大的发射电流密度。在849℃（亮度温度），利用亚微米粉体制备的含钪阴极的功函数约为1．55eV，电子发射常数为1．126A／cm^2K^2。同时，采用米拉曲线讨论了这类阴极的欠热特性和电子发射性能。     

Development of High Current-Density Cathodes With Scandia-Doped Tungsten Powders

The development of high current-density cathodes employing scandia-doped tungsten powders is reviewed in this paper. A matrix with a submicrometer microstructure characterized by uniformly distributed nanometer particles of scandia is believed to play a dominant role in the improved emission capability of these cathodes. Space-charge-limited current densities of over 30 A/cm² at 850 degC_b have been repeatedly obtained for many runs of cathodes fabricated from the different batches of scandia-doped tungsten powders. A lifetime of over 10000 h at 950-degC_b 2-A/cm² dc loading in a test diode has been achieved. Periodic high current-density pulse testing was also carried out during the test. The performance for both the dc and pulsed current densities remained stable. When tested at Stanford Linear Accelerator Center in a cathode life test vehicle with a Pierce gun configuration, the cathode operated for 500 h at 1170 degC _b, with a pulsed loading of 100 A/cm² and with less than 5% degradation in current density. The outstanding performance of these cathodes is attributed to a surface multilayer of Ba-Sc-O of about 100-nm thickness that uniformly covers the W grains with nanometer-size particles distributed on the growth steps. The layer is formed after proper activation by diffusion of free or ionic Sc together with Ba and O from the interior of the cathode to its surface. This highly mobile, free, or ionic Sc is liberated from constituents produced during impregnation and activation by reactions between the matrix materials and impregnants     

场致电子发射阴极及其制备方法的研究

文章对石墨、金刚石、非晶碳及碳纳米管等常用场发射冷阴极材料的结构、在场发射方面的应用和发展进行了介绍和分析,认为碳纳米管是场发射冷阴极的首选材料。并结合其原理和性能对电弧放电法、脉冲激光熔蒸法、化学气相沉积法、等离子增强化学气相沉积法等场发射阴极制备方法进行了探讨,认为等离子增强化学气相沉积法因可以实现低温原位生长而具有较好的发展趋势。     

场发射冷阴极的稳定性和可靠性研究

讨论了清洁处理（ＣＰ）对ＦＥＣ电子发射的影响。实验结果表明：ＣＰ能有效激活长时间存放于恶劣环境的ＦＥＣ的电子发射；还研究了场热成形（ＦＨＦ）对提高ＦＥＣ电子发射稳定性和可靠性和作用。实验发现，正确选择阳性工进行必要的真裕除气，对防止尖由于真空电弧而造成的破坏有破坏有重要意义。ＦＨＦ对尖端表面的微观状态具有强烈的影响，具体表面尖端有效功函数ψ才尖端场增强因子β的改变上，经过ＣＴ和ＦＨＦ处理，得到了发     

从第二届国际真空电子源会议(IVESC''98)看热阴极研究现状

介绍第二届国际真空电子源会议反映的有关微波管和显像管热阴极研究概况。     

A Study of Semitransparent Cathodes on the Performance of Top-Emitting Polymer Light-Emitting Diodes

This work reports the influence of semitransparent cathodes, which were made of Ca or Al covered with a thin layer of Ag, on the performance of poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylene vinylene) (MEH-PPV)-based top-emitting polymer light-emitting diodes (T-PLEDs). The physical properties of the semitransparent cathodes alter the optical microcavity of T-PLEDs and adjust the output characteristics of the electroluminescence (EL). The bright, red-emissive, MEH-PPV-based T-PLED, with Ca(10 nm)/Ag(20 nm) as the semitransparent cathode, exhibited 3.6 cd/A, 38.7 nm, and (x = 0.67, y = 0.33) for the luminous efficiency, full-width at half-maximum of the EL, and Commission International de I'Eclairage coordinate, respectively. The favorable performance can be attributed to the formation of an appropriate microcavity structure, which results in spatial redistribution and enhances the out-coupling of EL emission in the direction of the surface normal.     

用于热阴极的热子绝缘层研究

研究了热子涂层的原材料粒度对热子绝缘层质量的影响,粒度过细或过粗,涂层附着不均匀,烧结后涂层表面开裂、起皮、粗糙、掉粉严重。采用粒度级配的配比方案制备了氧化铝涂层,电镜分析表明,涂层致密,质量得到明显改善;与原有工艺相比,氧化铝涂层抗压能力提高了1倍。     

浸渍钡钨阴极表面同步辐射光电子谱研究

为了解浸渍钡钨阴极表面各元素的化学状态,采用同步辐射光电子谱技术对激活前后的阴极表面进行了研究。结果表明,与激活前相比,经1150℃×90min 高温激活后,阴极表面吸附层厚度减薄,吸附C 完全消失,O 含量明显升高,W 含量增加1 倍,Ba 含量增加2 倍。另外,阴极表面的O1s、W4f 和Ba3d 等的谱峰均向高结合能方向显著位移。分析认为,激活后的阴极表面分布的吸附氧,使W 基体以及阴极表面的Ba 均产生吸附氧化,Ba 在阴极表面主要以吸附化合物Ba_m?O_n(m≤n)的形式存在。     

金属涂敷硅锥阴极的工艺研究

本文比较了金属和硅两种场发射阴极的优缺点，研究了将两者优点结合在一起的金属涂敷硅阴极的制造工艺，比较了电镀法和溅射法制备的金属涂层对硅的附着力；采用先溅射后电镀的两步工艺制作出了较为理想的包全硅尖阵列。     

轴承压印字符自动识别算法的研究

为了方便轴承的生产和管理,针对轴承上字符的特点,提出了一种自动识别轴承压印字符的方法。首先借助环形光源,利用"反光差"产生并采集字符图像;然后利用随机Hough变换定位轴承圆心,并确定目标字符的位置;通过对单个字符进行仿射变换矫正字符区域;最后提取轮廓层次特征,并使用支持向量机识别。实验表明,该方法能够实现轴承字符的自动识别,并能满足实时性和识别率的要求。     

ZnO-Ni壳核丝状阴极场发射特性研究

采用水热法在Ni丝上制备锥状ZnO,形成ZnO-Ni壳核丝状阴极。采用X射线衍射分析仪进行物相分析,表明该ZnO具有沿002面生长的取向。用扫描电子显微镜(SEM)观察其表面形貌,表明Ni的表面生长有一层分布均匀的锥状ZnO。通过场发射性能测试,结果表明ZnO-Ni壳核丝状阴极具有比平面结构中的ZnO纳米锥阴极更优良的场发射性能,并对该结果进行讨论。     

提高PZT阴极电子发射性能的实验研究

实验研究了提高PZT(锆钛酸铅)阴极电子发射性能.在电子发射快极化反转机理的基础上,分析了电流发射密度随激励场强增大的原因.通过电极绝缘保护层改散了阴极的表面击穿特性,通过等静压工艺改善了阴极的体击穿特性和通过Mn2+的添加提高材料本生的耐电压强度,从而提高了施加在阴极上的激励场强值.实验数据显示等静压工艺、高的激励场强、绝缘保护层、Mn2+的添加等均有利于阴极的电流发射,发射电流密度提高到123 A/cm2.     

Graphite-Based Blade-Type Field Emission Cathodes

Semiconductors - In this work, the blade-type field emission cathodes (BFECs) of original construction have been developed and produced. As the basis of the cathodes the (110)-cut silicon wafers...     

覆锇膜阴极表面同步辐射光电子谱研究

为何浸渍阴极表面覆一层高功函数的锇(Os)膜后发射能力可以显著增加?这是一个长期未搞清的重要问题.该文在对阴极进行发射性能测试和扫描电镜分析的基础上,利用同步辐射光电子谱装置,对覆钨(W)膜阴极和覆Os膜阴极表面的元素成分及化学状态进行了全面系统的研究.结果表明,覆Os膜阴极的电子发射能力是覆W膜阴极2.65倍;与覆W膜相比,覆Os膜使阴极表面的钡(Ba)原子和低结合能态的吸附氧(O)原子分别增加了40％和56％.进一步分析认为,Os膜具有易氧化及氧化物易分解的特性,这一特性决定了覆Os膜阴极在激活后可以获得更多的超额钡Ba+(a),并因此具备更高的电子发射能力.     

单晶和多晶LaB6阴极发射性能的实验研究

讨论了由国内外3个不同来源的六硼化镧（LaB6)制成的阴极的发射性能，用标号1^#,2^#,3^#表示，其中1^#是LaB6单晶阴极，2^#,3^#分别是国外和国产的多晶阴极。实验主要测试了它们的发射特性，并作了简单分析，同时运用扫描电子显微镜、扫描俄歇微探针，X射线晶格衍射分析等手段对LaB6材料进行了分析，比较了LaB6材料质量与发射性能的关系。文中还对部分阴极电子学的重要结信纸及典型数据处理方法作了补充。     

Porous Cathodes for Implantable Hybrid Cells

The in vivo power output of implantable power sources using porous platinum- or palladium-black cathodes is approximately four to five times greater than ones using commercially available cathodes of platinum black dispersed in Teflon. Porous electrodes produce a much lower foreign-body reaction than electrodes with plastic binders. Comparison of BET surface-area measurements for the powders and compacted electrodes illustrate that there is an approximate 20-percent decrease in surface area following compaction. The particle size, distribution, and shape of the powders were studied with the aid of scanning electromicrographs. In vitro galvanostatic measurements were made on the implantable power sources to study the electrochemical activity before implantation.     

Stabilizing High-Nickel Cathodes with High-Voltage Electrolytes

Electrolytes connect the two electrodes in a lithium battery by providing Li⁺ transport channels between them. Advanced electrolytes are being explored with high-nickel cathodes and the lithium-metal anode to meet the high energy density and cycle life goals, but the origin of the performance differences with different electrolytes is not fully understood. Here, the mechanisms involved in protecting the high-capacity, cobalt-free cathode LiNiO₂ with a model high-voltage electrolyte (HVE) are delineated. The kinetic barrier posed by a thick surface degradation layer with poor Li⁺-ion transport is found to be the major contributor to the fast capacity fade of LiNiO₂ with the conventional carbonate electrolyte. In contrast, HVE reduces the side reactions between the electrolyte and the electrodes, leading to a thinner nano-interphase layer comprised of more beneficial species. Crucially, the HVE leads to a different surface reorganization pathway involving the formation of a thinner nanoscale LiNi₂O₄ spinel phase on the LiNiO₂ surface. With a high 3D Li⁺-ion and electronic conductivity, the spinel LiNi₂O₄ reorganization nanolayer preserves fast Li⁺ transport across the cathode–electrolyte interface, reduces reaction heterogeneity in the electrode and alleviates intergranular cracking within secondary particles, resulting in superior long-term cycle life.     

新型双区阴极结构体效应二极管

常规的GaAs体效应二极管的阴极结构多采用欧姆阴极,在毫米波频段(W 波段),器件的转换效率小于1%.介绍了一种新型的双区阴极结构在W 波段体效应二极管中的实现,并研制出了样品器件.采用此种结构,可以显著提高毫米波器件的输出功率和转换效率.     

Field-Emission Cathodes Based on Microchannel Plates

Semiconductors - The existing methods of fabricating low-field cathodes do not permit the development of device structures that comply with the requirements of developers of systems. In this work,...     

A Review on the Status and Challenges of Cathodes in Room-Temperature Na-S Batteries

The cathode materials for sodium-sulfur batteries have attracted great attention since cathode is one of the important components of the sodium-sulfur battery, and there are cathode materials that have high capacity, non-toxicity, and cost-efficiency. Nevertheless, due to their low Coulombic efficiency and proneness to cycling decay, the practical application of the sodium–sulfur battery has always been suppressed. In terms of the responsibility of these problems, the polysulfide shuttle and the sluggish kinetics are the main culprits. To address these issues, impeding the notorious reaction between polysulfide intermediates on the cathode and improve the kinetics reaction on the anode are extremely important. Herein, a comprehensive review is prepared of different approaches to increasing the electrochemical performance and strengthening the stability of cathodes. The influences of various choices and the consequent properties of the cathode in relation to the whole sodium–sulfur battery performance is investigated. Finally, the current research challenges related to cathodes for sodium–sulfur batteries and future perspectives are also discussed.