Surface evaluation of LiNbO3 and LiTaO3 crystals etched using fluorine system gas plasma reactive ion etching

The etching characteristics of LiNbO₃ and LiTaO₃ single crystals have been investigated by performing plasma reactive ion etching (RIE) with CF₄/Ar, CF₄/H₂, and CF₂/Ar/H₂ gas mixtures. The etched surface was evaluated by atomic force microscopy and X‐ray diffraction. The in situ surface temperature of the sample was measured during RIE. F atoms exist in the contamination layer on the surface etched using mixtures of CF₄, Ar, and H₂ gases. The etch rate was dependent on the crystal orientation. The etch rate of LiTaO₃ was less than that of LiNbO₃. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 149(2): 18–24, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10365     

Synthesis and characterization of PZT: CF magnetoelectric composites

Here, we report the structural, dielectric, ferroelectric, piezoelectric and magnetic properties of ME composites of Lead Zirconate Titanate (PZT) and Cobalt ferrite (CF) with compositional formula (1?x) PbZr_0.55Ti_0.45O₃ + (x) CoFe₂O₄, (x = 0.00, 0.05, 0.10, 0.15 and 1.00 by weight). The samples were synthesized by conventional solid state reaction. The formation of perovskite tetragonal and spinel structure in the composites are confirmed by X-ray diffraction studies. Microstructural study of all samples was done by SEM analysis and average grain size was also calculated. The dielectric properties of samples were studied as a function of frequency and as a function of temperature (30°C – 500°C) respectively. P-E hysteresis loop at room temperature and piezoelectric coefficient were measured to study the ferroelectric and piezoelectric properties. To confirm the ferromagnetic behavior of the composites M-H hysteresis loop measurement was carried out. The Magnetoelectric voltage coefficient (dE/dH) was measured as a function of applied DC magnetic field. The maximum ME output of 389μV/ (cm.Oe) was observed for the composite with x = 0.15.     

塑壳断路器不同结构触头灭弧系统吹弧磁场的分析

对塑壳断路器内部的触头灭弧系统结构进行改动,其触头打开电弧燃烧时的吹弧磁场亦会有相应的改变。应用三维有限元软件ANSYS分析了4种不同触头灭弧系统结构的吹弧磁场,对比了4个模型在通以相同电流的情况下,电弧中心线的磁感应强度B以及电弧受到的磁吹力。为增强吹弧磁场的磁吹力、提高触头灭弧系统的灭弧性能提供了方法和思路。     

旋气吹弧式SF6断路器及其三维气流场特性的仿真

为了提高断路器的弧后介质恢复速度,笔者以500 kV单断口高压SF6断路器为研究对象,提出了在气体通道的上游增加旋气槽的设想,将传统的轴向吹弧改进为旋转吹弧。对有旋气槽和无旋气槽两种结构在空载开断过程中灭弧室内气流的流动特性进行了数值仿真,仿真结果表明:喷口上游加旋气槽,能实现将电弧轴向运动变为旋转运动的目的;有旋气槽时,动静触头之间的高速气流比无旋气槽结构时的高速气流更为集中,有利于负载情况下电弧能量的逸散。     

Interruption capability of CF/sub 3/I Gas as a substitution candidate for SF/sub 6/ gas

We studied the interruption performance of CF₃I gas because its environmental effect is smaller than that of SF₆ gas with a model arc-extinguishing chamber. First, we measured the arc time constant and arc power loss coefficient using Mayr's equation. Comparing CF₃I with other gases, the arc time constants are SF₆3I2< H₂2. The arc power loss coefficient is H₂>SF₆ >CO₂>Air>N₂ >CF₃I. Next, we evaluated the short line fault (SLF) interruption capability by measuring the di/dt-dv/dt characteristic. Consequently, the SLF interruption performance of pure CF₃I was about 0.9 times that of SF₆. However, CF₃I application to gas insulated switchgear (GIS) and gas circuit breakers (GCB) is difficult because the liquefying temperature of the gas is high. Therefore, we adopted a countermeasure to obtain a lower liquefying temperature mixing CF₃I with CO₂. The result showed that the SLF interruption performance of the mixture approximated that of pure CF₃I when the ratio of CF₃ I exceeds 20%     

Bottom electrode etching effect on the electrical properties of lead strontium titanate thin film

(Pb_0.4Sr_0.6)TiO₃ thin films were prepared by a modified sol-gel method on Pt/Ti/SiO₂/Si substrates, where lower figure of merit of about 16% was observed in spite of higher tunability above 58%. The electrode surface was etched with different CF₄ and Ar gas ratios to modify the surface roughness. The electrical properties of PST thin films were investigated as a function of etching condition and film thickness. With changing CF₄/(Ar+CF₄) gas composition, the dielectric loss and the figure of merit were apparently affected which can be explained in terms of the surface roughness of Pt bottom electrode. When the Pt electrode surface was etched by using CF₄/(Ar+CF₄) = 20% gas mixture, the improvement above 25–27% in dielectric loss and figure of merit was observed, according to the decreased rms value of Pt surface of ∼30%, from 1.8 to 1.2 nm. The etching effect was found to be dominant for the dielectric loss and the thinner films.     

SF_6混合气体灭弧介质的选择

首先考察了16种常用气体构成的SF_6混合气体。通过分析其液化温度、介电强度、电弧产物的毒性及腐蚀性、热物理性质和传输特性以及价格成本,认为SF_6/N_2混合气体可以代替纯SF_6做为GCB(气体断路器)在低温环境下的灭弧介质。之后,研究了SF_6/N_2的开断特性。研究结果证明,SF_6/N_2混合气体具有较好的开断特性。     

Melt synthesis and characterization of complexed perovskite-oxides in the system of A2+(B+ 2/5B6+ 3/5)O3 - A3+(B+ 3/5B6+ 2/5)O3

In order to synthesize various Perovskite ABO₃ type compounds and their solid solutions, we have applied a novel “melt synthesis technique” rather than conventional solid state reaction techniques. In the melt synthesis, the mixture of oxides or their precursors is melted in a short period of time (1–60 sec) by a strong light radiation in an arc imaging furnace. A spherical molten sample where multiple cations were mixed homogeneously was directly solidified on a copper hearth with a rapid cooling of 10² K/sec. Solid solutions based upon 1:1 ordered Perovskite in the system of Sr(Li_2/5W_3/5)O₃-La(Li_3/5W_2/5)O₃ were synthesized in this technique.     

讨论和分析近期低压电器的若干新技术

分析和讨论了近期低压电器的若干新技术,如断路器单断点与双断点分断技术及其系列结构方案比较、永磁接触器与智能操作结合更加节能、根据电弧测试与气吹机理设计新型灭弧室、虚拟样机的应用提高了断路器分断能力。这些新技术有助于低压电器的技术创新。     

真空灭弧室性能参数分析

分析了真空灭弧室的性能参数。详细分析了触头结构、真空度、真空电弧温度的影响、触头间隙的确定、屏蔽罩厚度以及真空灭弧室的并联运行。提出真空开关在低压电器领域将有广阔的发展前景。     

Preparation of lithium-ion polymer battery using LiNi1/3Co1/3Mn1/3O2 as a cathode material and its electrochemical properties

In this work, LiNi_1/3Mn_1/3Co_1/3O₂ powders were synthesized from co-precipitated spherical metal hydroxide. In the voltage range of 2.8–4.2, 2.8–4.4, and 2.8–4.6 V, the discharge capacities of LiNi_1/3Mn_1/3Co_1/3O₂ electrode were 163, 177, and 193 mAh⋅g⁻¹, respectively. A gel polymer electrolyte (GPE) was also prepared using polyoxyalkylene glycol acrylate (POAGA) as a macromonomer. LiNi_1/3Mn_1/3Co_1/3O₂/GPE/graphite cells were prepared and their electrochemical properties were evaluated at various current densities and temperatures. The ionic conductivity of the GPE was more than 6.2 × 10⁻³ S⋅cm⁻¹ at room temperature. POAGA-based cells were showed good electrochemical performances such as rate capability, low-temperature performance, and cycleability.     

永磁磁场对开关电器灭弧性能影响的研究

在分析开关电器直流电弧熄灭原理的基础上 ,在触头弧隙加装不同规格的永磁体 ,通过不同结构永磁磁场对灭弧性能影响的分析及试验研究结果表明 ,在开关电器弧隙中加装永磁体后 ,永磁产生的磁场可提高灭弧能力 ,缩短燃弧时间。     

Investigation of a new extinguishing principle for a gas circuit breaker

A self-extinguishing principle of a gas circuit breaker (GCB) without puffer action (autopuffer GCB) using an external magnetic field was investigated to improve the interrupting capability in the small current region (several kA). Properties of the rotating speed of an arc, the arc voltage, and the gas pressure rise in an expansion space under the external magnetic field were studied experimentally. The relation between the interrupting capability and the radial magnetic flux density in the autopuffer GCB with a permanent magnet (magnet-assisted autopuffer GCB) was obtained experimentally and also analyzed numerically. The results are summarized as follows.

• 1 The arc column is driven in the azimuthal direction by the radial component of the external magnetic field.
• 2 The rotating speed of the arc driven by the radial magnetic field of a permanent magnet remains constant in the arc current range below several kA, and it decreases with an increasing current in the current above several kA.
• 3 Since the arc rotation raises the arc voltage and gas pressure in the expansion space, the gas flow from the expansion space to the arc increases in the vicinity of current zero. The interrupting capability is then improved in the small current region.
• 4 It is confirmed that the magnet-assisted auto-puffer GCB has a good interrupting capability not only for the large current region but also for the small current region.

     

Measurement of arc properties and spectrum intensity in AC arcs surrounded by plastics

This paper describes experimental results on the arc‐quenching properties under the condition of being surrounded by plastic found in low‐voltage circuit breakers. The alternating current used is from 500 to 1100 A(rms) with 60‐Hz frequency. The plastic materials investigated here are polymethylpentene (? C₃H₅? ), polymethylmethacryl‐ate (? C₅H₈O₂? ), polybutyleneterephthalate (? C₁₂H₁₄O₄? ), polycarbonate (? C₁₆H₁₈O₃? ), and PTFE (? C₂F₄? ). In conjunction with the usual arc current and voltage measurements, two images of spectrum intensity of 511 and 522 nm emitted from copper electrode vapor are detected simultaneously by using two bandpass filters. A high‐speed digital video technique (4500 frames per second) is used for analyzing the transient space movement of copper vapor. The arc voltage is strongly influenced by the plastic materials rather than the arc current. Especially in the case of ? C₃H₅? , the magnitude of the arc current was strongly limited by its high arc voltage. On the other hand, in the case of ? C₂F₄? , the arc cannot be interrupted and the arc voltage is the lowest value of all. The arcing period is also much influenced by the type of plastic material (the shortest and longest were ? C₃H₅? and ? C₂F₄? , respectively), while it shows almost no change with amplitude of arc current. The spectroscopic images of copper vapor obtained by high‐speed video for transparent plastics of ? C₅H₈O₂? and ? C₁₆H₁₈O₃? showed that the vapor expanding speed of the former is considerably faster than that of the latter. The results indicate strongly that the arc‐quenching property is affected by the ablation and blast speed of arc‐surrounding plastic materials. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 140(1): 38–47, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10002     

Ferroelectric Property and Crystal Structure of KNbO3 Based Ceramics

Rietveld refinement analysis was carried out to obtain the knowledge on the solid solution structure of the La and Fe co-doped KNbO₃ ceramics. The diffraction data was well fitted with tetragonal space group P4mm, and showed that La and Fe located at K and Nb sites in KNbO₃ perovskite, respectively. The sum of both occupancy ratios agreed almost well with the doping content. Furthermore, the effects of MnO₂ addition on the ferroelectric properties and crystal structure of the La and Fe co-doped KNbO₃ ceramics were investigated. MnO₂ addition strongly affected the ferroelectric and piezoelectric properties, because the valence of Mn ions changed from Mn^{4 +} to some extents of Mn^{3 +} and Mn²⁺, which were suggested by XAFS analysis.     

Suppression of interface reaction of LiCoO2 thin films by Al2O3-coating

Al₂O₃-coated LiCoO₂ thin films were prepared to characterize the effects of coating in detail. The LiCoO₂ film electrodes served as effective pristine cathodes to investigate the interface reaction between a cathode and electrolyte because they have wide and smooth surface and do not contain conducting agents (such as carbon) or binders. The electrochemical properties, surface morphology, and concentration profile (vs. depth) were characterized to identify the effects of coating. The Al₂O₃-coated film showed a much improved rate capability and cyclic performance compared with those of the pristine film. Specifically, based on the results of SIMS analyses and SEM images, dissolution of transition-metal ions and surface damage during storage at high temperature were suppressed by Al₂O₃ coating. This result directly shows the successful protective effect of surface coating, which is associated with enhanced electrochemical properties of the coated film.     

Synthesis of fine Ca-doped BaTiO3 powders by solid-state reaction method—Part I: Mechanical activation of starting materials

Fine (Ba_0.98Ca_0.02)_1.002TiO₃ powders for high capacitance multilayer ceramic capacitors (MLCCs) application were synthesized by solid state reaction method. The effects of mechanochemical activation using high energy milling and the starting materials properties on the reaction temperature and on the final powder properties were investigated. Previous heavy milling of BaCO₃ and the adoption of fine, anatase-rich TiO₂ phase were effective in decreasing the reaction temperature and in increasing the tetragonality (=c/a). BaCaTiO₃ powders with a tetragonality of 1.0097, an average particle size of 213 ± 43 nm and a specific surface area of 6.30 m²/g were acquired after heat treatment at 985 °C for 2 h. MLCCs utilizing this developed powder showed superior dielectric and temperature characteristics to those with conventional, Ca-free BaTiO₃ powder.     

Microwave Dielectric Characteristics of MgTiO<Subscript>3</Subscript>/CaTiO<Subscript>3</Subscript> Layered Ceramics

MgTiO₃/CaTiO₃ layered ceramics with differently stacking were fabricated and the microwave dielectric properties were evaluated with TE₀₁₁ mode. With increasing CaTiO₃ thickness fraction, the resonant frequency decreased and the dielectric constant increased with a near-linear relation for the bi-layer ceramics, while the values of the tri-layer MgTiO₃/CaTiO₃/MgTiO₃ ceramics with thickness ratio of 1:1:1 derived much from the curves of the bi-layer ceramics. The finite element method was used to give an explanation for the differences between the bi-layer and tri-layer ceramics.     

New method for estimating CF of pitch-regulated wind turbines

This paper presents a new formulation for wind turbine capacity factor (CF) estimation using wind speed characteristics at any site and the power performance curve parameters of any pitch-regulated wind turbine. Compared to the existing model, the proposed formulation is simpler and results in more accurate CF estimation. The accuracy of the proposed model is verified using measured data from an existing wind farm. Four illustrative case studies and parameter sensitivity analysis are presented to test the effectiveness of the model in turbine-site matching applications.     

Molecular structure of a random copolymer film by plasma‐enhanced CVD from a mixture of cyclohexa hydrocarbons

An important issue in the polymerization of a polymer film by plasma‐enhanced chemical vapor deposition (PECVD) is how to control the polymer structure. As is generally recognized, it is extremely difficult to control the process because it is very complex. For example, various precursors in the plasma arise from fragmentation of source monomers, which can easily change by varying the plasma conditions. High‐energy electrons and ions in the plasma bombard the surface of the deposited film and affect the chemical reaction on the film. Moreover, the droplets that arise from the reactor wall by sputtering will accumulate on the film. However, if we aim to fabricate only a photonically functional polymer film, we will be able to find a solution. In this paper, we propose copolymerization from two types of monomers; one type is used as jointing materials by cracking, and the other is used as a photonic functional segment without serious deformation. This difference of action arises from a difference in the formation enthalpy. To confirm this idea, as an initial step, we copolymerized a film from a mixture of benzene (C₆H₆) as the functional segment and cyclohexene (C₆H₁₀) as the jointing material under the low radio frequency power. The deposited film consists of sp² bonding clusters surrounded by sp³ bonded (alkyl) networks. We confirmed that the sp² bonding clusters mostly belong to phenyl, with a few belonging to olefins arising from decomposed C₆H₆. In addition, the amount of sp² bonding increases proportionally with increasing ratio of C₆H₆ in the mixture, and the ratio of phenyl in the film becomes comparable to that of polystyrene. From these facts, we speculate that C₆H₁₀ acts as the jointing material and C₆H₆ as the functional segment. Additionally, we introduced tetrafluorocarbon (CF₄) to the plasma. CF₄ decomposes with a smaller energy than C₆H₁₀, and it forms mainly fluorine and CF₃ radicals. The fluorine radical pulls out hydrogen from the film and reacts to form dangling bonds in the film. Moreover, we speculate that they will terminate the dangling bonds. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.