使用扫描力显微镜测量表面电容

叙述了两种类型（接触模式和非接触模式）扫描电容显微镜的工作原理，并叙述了不同类型扫描电容显微镜的应用领域。接触模式扫描电容显微镜可以得到样品形貌像、电容像和载流子密度像，非接触模式扫描电容显微镜可以得到样品形貌像、电容梯义像和分布像。

如何选择表面电容式触摸显示屏控制器

对于所有电容式触摸屏,控制器是其重要部分,所以正确地选择控制器是产品成功与否的关键。本文将讲述如何选择表面电容式触摸屏的控制器,以及如何集成控制器及其相应的软件。

螺旋表面极板电容式传感器的灵敏场分析

气固两相流质量流量的检测和控制是工业上长期未能有效解决的难题。从工业角度出发,采用电容层析成像技术建立了一种改进型螺旋表面极板电容式传感器。通过有限元仿真的方式,分析了极板张角、管壁介电常数、管壁厚度对灵敏场分布和均匀性误差参数的影响。通过仿真分析,确定了各传感器模型参数的取值范围,为灵敏场分布的改善、传感器的优化设计和传感器系统性能的提高提供了必要的理论基础。

电容器表面清灰系统

电容器表面漆膜附着力是影响电容器良好的喷漆涂装的关键。良好的电容器表面处理方法又是影响电容器表面漆膜附着力的关键。目前,电容器表面抛丸打毛是电容器表面处理的常用方法之一,但是抛丸打毛后遗留在电容器表面的残灰又是影响电容器表面附着力的不可忽视的原因。传统的表面清灰方法,耗时耗力,且质量不高。电容器表面清灰系统,它清扫均匀,不留死角,大大提高了电容器表面清灰质量。

科技成果转化助企业创新发展——解读半导体瓷介电容器技术成果转化与宏科新材料公司的成长

本文通过解析电子科技大学所拥有的半导体瓷介电容器技术成果,与成都宏明电子股份有限公司合作转化,创办高新技术企业—成都宏明电子科大新材料有限公司的案例,阐明:科技成果的转化不同于商品交换的一次市场交易行为,而是转化双方资源的重新有效配置和科技成果再创造的过程。因此评价一项成果是否转化成功的标准不仅仅是计算它直接给企业创造的经济价值,更重要的是是否影响企业未来走势从而促进企业创新发展。

Co(OH)2/rGO电极储能动力学实验设计

随着能源在现代社会的作用日益凸显,储能电极材料的研究越来越受到关注。越来越多的新型电极材料显示出既不是纯电容性(超级电容器,表面电容控制)也不是纯法拉第性(电池,扩散控制)的电化学特性。为了阐明电极的这2种电化学储能行为差异,该文采用在实验课堂上就可以进行的简单快速的方法制得Co(OH)2/还原氧化石墨烯(rGO)复合电极。在1 mol/L KOH水溶液体系中,对该电极进行了不同小扫速下的循环伏安测试(CV)。根据电流i与扫速v的幂律关系对电极反应的表面控制与扩散控制贡献进行定量计算,并探讨其与Co(OH)2电极在相同测试条件下的电化学行为差异。该实验将当前的储能研究热点整合成一个物理化学实验,有利于学生学会电池材料、超级电容器材料及其储能原理等相关概念,掌握电极材料储能动力学分析方法和原理,学习一种储能电极材料的制备方法,由此激发学生科学研究的兴趣。

Laser processing effects on Ti−45Nb alloy surface,corrosive and biocompatible properties

The Ti−45Nb(wt.%)alloy properties were investigated in relation to its potential biomedical use.Laser surface modification was utilized to improve its performance in biological systems.As a result of the laser treatment,(Ti,Nb)O scale was formed and various morphological features appeared on the alloy surface.The electrochemical behavior of Ti−45Nb alloy in simulated body conditions was evaluated and showed that the alloy was highly resistant to corrosion deterioration regardless of additional laser surface modification treatment.Nevertheless,the improved corrosion resistance after laser treatment was evident(the corrosion current density of the alloy before laser irradiation was 2.84×10^(−8)A/cm^(2),while that after laser treatment with 5 mJ was 0.65×10^(−8)A/cm^(2))and ascribed to the rapid formation of a complex and passivating bi-modal surface oxide layer.Alloy cytotoxicity and effects of the Ti−45Nb alloy laser surface modification on the MRC-5 cell viability,morphology,and proliferation were also investigated.The Ti−45Nb alloy showed no cytotoxic effect.Moreover,cells showed improved viability and adherence to the alloy surface after the laser irradiation treatment.The highest average cell viability of 115.37%was attained for the alloy laser-irradiated with 15 mJ.Results showed that the laser surface modification can be successfully utilized to significantly improve alloy performance in a biological environment.

Determination of the Real Surface Area of Palladium Electrode

Four methods, including voltammetric measurement of double layer capacitance, surface oxides reduction, under potential deposition of Cu and carbon monoxide （CO） stripping have been applied to evaluate the real surface area of a polycrystalline Pd （pc-Pd） electrode. The results reveal that the second and third methods lead to consistent results with deviations below 5%. And from the determined double layer capacitance and CO stripping charge, it is deduced that the double layer capacity unit area is 23.1±0.4μF/cm2 and the saturated CO adlayer should be ca. 0.66 ML in order to ensure that the real surface area as determined is consistent with the other two techniques. The applicability as well as the attentions when applying these techniques for the determination of the real surface area of pc-Pd electrodes have been discussed.

Synthesis, characterization and electrochemical performance of AlF_3-coated Li_(1.2)(Mn_(0.54)Ni_(0.16)Co_(0.08))O_2 as cathode for Li-ion battery

Li-rich layered transitional metal oxide Li1.2(Mn0.54Ni0.16Co0.08)O2 was prepared by sol-gel method and further modified by AlF3 coating via a wet process. The bare and AlF3-coated Li1.2(Mn0.54Ni0.16Co0.08)O2 samples were characterized by X-ray diffraction(XRD), scanning electron microscope(SEM), and high resolution transmission electron microscope(HRTEM). XRD results show that the bare and AlF3-coated samples have typical hexagonal α-Na Fe O2 structure, and AlF3-coated layer does not affect the crystal structure of the bare Li1.2(Mn0.54Ni0.16Co0.08)O2. Morphology measurements present that the AlF3 layer with a thickness of 5-7 nm is coated on the surface of the Li1.2(Mn0.54Ni0.16Co0.08)O2 particles.Galvanostatic charge-discharge tests at various rates show that the AlF3-coated Li1.2(Mn0.54Ni0.16Co0.08)O2 has an enhanced electrochemical performance compared with the bare sample. At 1C rate, it delivers an initial discharge capacity of 208.2 m A·h/g and a capacity retention of 72.4% after 50 cycles, while those of the bare Li1.2(Mn0.54Ni0.16Co0.08)O2 are 191.7 m A·h/g and 51.6 %, respectively.

Study on the heat transfer of cross flow in vertical upward tubes

A special device was designed to measure temperature difference in this study of heat transfer of water and oil cross flow inside vertical upward tubes. A new heat transfer correlation was obtained for cross flow. The experimental results showed that the dependence of heat transfer on Reynolds is much smaller in a narrow space than that in a wide space. It was found that the heat transfer correlation of cross flow in a narrow space is obviously different from that in a wide space, and that the heat transfer correlation obtained in a wide space may not be applicable to the cross-flow heat transfer in a narrow space. Further, the single-phase heat transfer capability of water cross flow was compared with that of oil cross flow. The experimental results showed that the average heat transfer coefficient of water is about 2～3 times that ofoil when they have the same superficial velocity.

Nano-Li3V2（PO4）3/C Synthesized by Thermal Polymerization Method as Cathode Material for Lithium Ion Batteries

A nano-Li3V2（PO4）3/C powder was successfully prepared by a thermal polymerization method. The particle sizes of the intermediate product powder and the final product Li3V2（PO4）3 are all less than 200 nm. The carbon is partially coated on the surface of Li3V2（PO4）3 particles and the rest exists between particles with a total carbon content of 4.6wt%. This nano-Li3V2（PO4）3/C sample shows a discharge capacity of 124 mAh/g with-out capacity fading after 100 cycles at 0.1 C in the voltage rang of 3.0-4.3 V. Excellent rate performance is also achieved with a capacity of 80 mAh/g at 20 C in 3.0-4.3 V and 100 mAh/g at 10 C in 3.0-4.8 V. This study suggests that the thermal polymerization method is suitable to synthesize nano-Li3V2（PO4）3/C materials.

电容器

Y2000-62135-245 0019861采用 PECVD 氮化物用于混合信号和射频电路的高密度金属绝缘体金属电容器=High density metal insula-tor metal capacitors using PECVD Nitride for mixed sig-nal and RF circuits[会,英]/Kar-Roy,A.& Hu,C.//1999 IEEE Proceedings of InternationaI InterconnectTechnology Conference.-245～247(EC)

Supercapacitors based on high-surface-area graphene

Exfoliated graphite oxide was prepared by an improved Hummers method and was then reduced to graphene with hydrazine in the presence of ammonium hydroxide.N2adsorption–desorption measurement showed that graphene so obtained had a specific surface area as high as 818 m2/g.Galvanostatic charge/discharge curves demonstrated that the as-prepared graphene exhibited a specific capacitance of 186.9 F/g at a current density of 0.1 A/g and that about 96%of the specific capacitance was retained after 2000 cycles at a current density of 5 A/g.

Effect of surface area and heteroatom of porous carbon materials on electrochemical capacitance in aqueous and organic electrolytes

A series of porous carbon materials with wide range of specific surface areas and different heteroatom contents had been prepared using polyaniline as carbon precursor and KOH as an activating agent. Effect of surface area and heteroatom of porous carbon materials on specific capacitance was investigated thoroughly in two typical aqueous KOH and organic 1-butyl-3- methylimidazolium tetrafluoroborate/acetonitirle electrolytes. The different trends of capacitance performance were observed in these two electrolytes. Electrochemical analyses suggested that the presence of faradaic interactions on heteroatom-enriched carbon materials in organic environment is less significant than that observed in aqueous electrolytes. Thus, in aqueous electrolyte, a balance between surface area and heteroatom content of activated porous carbon would be found to develop a supercapacitor with high energy density. In organic electrolyte, the capacitance performance of porous carbon is strongly dependent on the surface area. The results may be useful for the design of porous carbon-based supercapacitor with the desired capacitive performance in aqueous and organic electrolytes.

Activated pyrolysed bacterial cellulose as electrodes for supercapacitors

In this paper, the bacterial celluloses(BCs) were pyrolysed in nitrogen and then activated by KOH to form a porous three- dimension-network electrode material for supercapacitor applications. Activated pyrolysed bacterial cellulose(APBC) samples with enlarged specific surface area and enhanced specific capacitances were obtained. In order to optimize electrochemical properties, APBC samples with different alkali-to-carbon ratios of 1, 2 and 3 were tested in two electrodes symmetrical capacitors. The optimized APBC sample holds the highest specific capacitance of 241.8 F/g, and the energy density of which is 5 times higher than that of PBC even at a current density of 5 A/g. This work presents a successful practice of preparing electrode material from environment-friendly biomass, bacterial cellulose.

Ultrathin Ni(OH)2 layer coupling with graphene for fast electron/ion transport in supercapacitor

Integration of fast electrochemical double-layer capacitance and large pseudocapacitance is a practical way to improve the overall capability of supercapacitor,yet remains challenging.Herein,an effective cyanogel synthetic strategy was demonstrated to prepare ultrathin Ni(OH)2 nanosheets coupling with conductive reduced graphene oxide(rGO)(rGO-Ni(OH)2)at ambient condition.Ultrathin Ni(OH)2 nanosheet with 3–4 layers of edge-sharing octahedral MO6 maximally exposes the active surface of Faradic reaction and promotes the ion diffusion,while the conductive rGO sheet boosts the electron transport during the reaction.Even at 30 A g−1,the optimal sample can deliver a specific capacitance of 1119.52 F g−1,and maintain 82.3%after 2000 cycles,demonstrating much higher electrochemical capability than bare Ni(OH)2 nanosheets.A maximum specific energy of 44.3 W h kg^−1(148.5 W kg^−1)is obtained,when assembled in a two-electrode system rGO-Ni(OH)2//rGO.This study provides an insight into efficient construction of two dimensional hybrid electrodes with high performance for the new-generation energy storage system.

What are the practical limits for the specific surface area and capacitance of bulk sp^2 carbon materials?

The possible practical limits for the specific surface area and capacitance performance of bulk sp^2 carbon materials were investigated experimentally and theoretically using a variety of carbon materials. We find the limit for the specific surface area to be 3500–3700 m^2 g^(-1), and based on this, the corresponding best capacitance was predicted for various electrolyte systems. A model using an effective ionic diameter for the electrolyte ions was proposed and used to calculate the theoretical capacitance. A linear dependence of experimental capacitance versus effective specific surface area of various sp^2 carbon materials was obtained for all studied ionic liquid, organic and aqueous electrolyte systems. Furthermore, excellent agreement between the theoretical and experimental capacitance was observed for all the tested sp^2 carbon materials in these electrolyte systems, indicating that this model can be applied widely in the evaluation of various carbon materials for supercapacitors.