Chemical Design and Thin Film Preparation of p-Type Conductive Transparent Oxides

Chemical design to find a new transparent conductive oxide having p-type conductivity has been proposed. Following the chemical design, we have selected CuGaO₂ and CuAlO₂ as candidate materials. CuGaO₂ thin films were prepared on silica glass substrates by RF sputtering method. The optical band gap of the film was estimated to be 3.4 eV. Positive sign of Seebeck coefficient demonstrated the p-type conductivity of the film. The dc conductivity of the film was 5.6 × 10^–3S·cm^-1 and the activation energy was 0.22 eV at room temperature. Because of rough texture of the film, the observed conductivity was not an intrinsic property of the material. Further, CuAlO₂ thin films were prepared by laser ablation. The film deposited in O₂ atmosphere of 1.3 Pa at 690°C showed higher optical transmission in visible and near-infrared regions than previously reported. Contribution of Cu 3d components to upper edge of valence band in CuGaO₂ and CuAlO₂ were confirmed by photoemission spectroscopic measurements.     

Defect-Property Correlations in Garnet Crystals. *VII: The Electrical Conductivity and Defect Structure of Yttrium Aluminum and Yttrium Iron Garnet Solid Solutions

The conduction mechanisms in yttrium aluminum and yttrium iron garnet solid solutions have been studied as a function of temperature, iron concentration and partial pressure of oxygen. At low concentrations of iron, ac conductivity and ionic transference measurements show the solid solution to be a mixed ionic-electronic conductor with an ionic mobility characterized by an activation energy of 2.6–2.8eV and a p-type electronic conductivity with activation energy of 3.0–3.3eV. High concentrations of iron cause a dramatic increase in the electrical conductivity connected with the formation of an Fe impurity band found to lie 1.9eV below the conduction band. Transport through this band is via an activated hopping process with an activation energy of 0.7eV for 6 fraction percent Fe. A defect model is presented which is consistent with our experimental observations including the conductivity maxima obtained at high PO₂'s for high Fe levels.     

Nonstoichiometry and Electrical Conductivity of Nanocrystalline CeO{2 - x}

We synthesized dense CeO polycrystals of 10 nm grain size and characterized their electrical conductivity, in order to determine whether the defect properties of nanocrystalline solids fundamentally differ from those of conventional materials. The nanocrystals exhibit enhanced electronic conductivity, greatly reduced grain boundary impedance, and a heat of reduction more than 2.4 eV lower per oxygen vacancy compared to their coarse-grained counterparts. We propose that defect formation at low energy grain boundary sites is responsible for these properties, and that nanocrystalline oxides represent bulk materials possessing the defect thermodynamics of interfaces.     

熔融碳酸盐燃料电池阴极材料的导电性

通过交流阻抗方法研究了熔融碳酸盐燃料电池阴极材料锂镍氧化物、锂钴氧化物和锂铁氧化物的导电性能。结果表明:锂镍氧化物电极的导电性最好,锂钴氧化物电极的导电性次之,锂铁氧化物电极的导电性最差;它们的导电性都随着温度的升高而按指数规律增加;在合成锂钴氧化物(或锂铁氧化物)的过程中,使Li2CO3轻微过量,可以提高锂钴氧化物(或锂铁氧化物)电极的导电性,而且在同一温度下,随着nLi∶nCo(或nLi∶nFe,摩尔比)值的增大,锂钴氧化物(或锂铁氧化物)电极的导电性显著增加。     

Low‐resistive and transparent AZO films prepared by PLD in magnetic field

Al₂O₃‐doped ZnO (AZO) thin films have been deposited onto glass substrates using a split target consisting of AZO (1 wt%) and AZO (2 wt%) by pulsed laser deposition with an ArF excimer laser (λ = 193 nm, 15 mJ, 10 Hz, 0.75 J/cm²). By applying a magnetic field perpendicular to the plume, the lowest resistivity of 8.54 × 10^?5Ω·cm and an average transmittance exceeding 91% over the visible range were obtained at a target‐to‐substrate distance of 25 mm for approximately 279‐nm‐thick AZO film (1.8 wt%) grown at a substrate temperature of 230 °C in vacuum. From cross‐sectional TEM observations and the XRD spectrum, a reason why the low resistivity (54 × 10^?5Ω·cm) was reproducibly obtained was considered to be due to the fact that a disorder of crystal growth originating in the vicinity of the interface between the substrate and the film was suppressed by application of the magnetic field and the c‐axis orientation took preference, giving rise to the increase of mobility. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 151(2): 40–45, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20026     

Modeling and Characterization of Electrical Transport in Oxygen Conducting Solid Electrolytes

A model for the electrical conductivity in acceptor-doped oxides which involves an association between the acceptor-dopants and oxygen vacancies resulting in donor centers is considered. The model relates the behavior of the electrical conductivity with the temperature, ambient atmosphere and band structure. The predictions of the model are compared to experimental data for ZrO₂:16% Y and SrCeO₃:5% Yb oxygen conductors and some band structure parameters have been determined.     

不可逆电穿孔时组织电导率变化对电场和温度的影响

为了研究不可逆电穿孔过程中组织电导率对组织内电场分布及温度的影响,采用有限元分析软件COMSOL建立了小鼠肝脏的球形肿瘤及椭球形肿瘤的数值模型;通过改变组织的电导率,得到肿瘤及正常组织内不可逆电穿孔电场、温度的分布情况。结果表明:组织电导率随着穿孔过程的发展逐渐增大。组织电导率变化前后,2种肿瘤模型中的各项数据如下:1)不可逆电穿孔电场消融的肿瘤体积与肿瘤总体积之比分别从0.867 7升至0.927 0(球形肿瘤)以及从0.451 1升至0.772 1(椭球形肿瘤);2)不可逆电穿孔电场造成正常组织损伤的体积与肿瘤总体积之比分别从0.745 9降至0.678 2(球形肿瘤)以及从0.816 4降至0.603 6(椭球形肿瘤);3)温升1℃的正常组织的最大体积只有肿瘤体积的1.16%,说明正常组织的温升对组织整体温度变化的影响较小。因此,组织不可逆电穿孔过程中,增大电导率能在促进电脉冲对肿瘤的消融效果的同时减小其对正常组织的损伤,且脉冲作用造成的组织温升不会造成组织的热损伤。     

化学交联方式对聚乙烯水树枝老化特性的影响

为研究化学交联对聚乙烯水树枝老化特性的影响,选用低密度聚乙烯（LDPE）、过氧化物交联聚乙烯、硅烷交联聚乙烯作为试验材料。采用水针电极法培养水树枝,用金相显微镜观测水树枝的形态,并统计了水树枝的尺寸和引发率;同时观测了试样的结晶形态,测定了试样的结晶度、交联度和杂质质量分数,并对比分析了交联前后及不同交联方式试样的电气...     

Featured Article: Use of Microhotplates in the Controlled Growth and Characterization of Metal Oxides for Chemical Sensing

Microhotplates are micromachined platforms with integrated heaters and contact electrodes that can be used as miniature substrates for metal oxide film growth. Fabricated as arrays, they enable efficient combinatorial studies to be performed on a single chip. A variety of growth methods are compatible with their use, including evaporation, sputtering, chemical vapor deposition, and deposition from pastes or sol gels using screen printing, drop deposition, or spin-coating. The microheater on each element may be used to control the temperature during deposition or for a post-annealing step such as sintering, while the film contact electrodes serve as a built-in monitor of the fabrication process. In chemical vapor deposition using arrays, the elements with heaters set above the lowest nucleation temperature for a given precursor are the only ones that will have film deposited on them, resulting in a kind of self-lithography. This review gives examples of different methods of film growth that have been employed on microhotplates with applications for chemical sensing, with an emphasis on the chemical vapor deposition method.     

覆冰绝缘子串泄漏电流与覆冰量及覆冰水电导率的关系

污秽与覆冰量是影响输电线路绝缘子冰闪电压的主要因素,因此有效预测污秽和覆冰量是防止发生冰闪事故的手段。本文通过人工气候室试验,模拟运行电压下覆冰量和覆冰水电导率对覆冰绝缘子泄漏电流的影响,提取了泄漏电流的三个特征量:泄漏电流脉冲幅值、谐波含量和电荷量,这三个特征量从不同角度描述了泄漏电流与覆冰量和覆冰水电导率的关系,并且得到了它们之间的回归方程式。基于泄漏电流特征量与覆冰量、覆冰水电导率的关系,提出覆冰绝缘子污冰预测神经网络模型,脉冲幅值、谐波含量和电荷量作为神经网络的输入量,污冰参数(ISP)作为神经网络的输出量。神经网络模型预测结果与试验测试结果对比分析可知,预测结果与试验结果的相对误差绝对值小于8.5%,因此本文提出的覆冰绝缘子污冰预测模型能够有效地对覆冰绝缘子ISP进行预测,为输电线路外绝缘的选择和设计提供参考依据,对于预防冰闪事故的发生有着重要的意义。     

反应合成AgSnO2电接触材料的组织与性能研究

采用反应合成技术和传统粉末冶金技术制备银氧化锡(AgSnO2)电接触材料。利用千瓦CO2激光器模仿电弧作用在试样表面产生局部熔化，对AgSnO2块体材料进行抗熔蚀性测试。对AgSnO：块体材料进行电导率测试和X射线衍射分析，对块体材料及冷拉拔的AgSnO2线材进行显微组织分析(扫描电镜、透射电镜)。研究结果表明，采用反应合成技术可以在银基体中合成尺寸细小、界面新鲜的SnO2颗粒，所制备的AgSnO2电接触材料中，微米级的SnO2颗粒系由纳米级的SnO2颗粒聚集而成I反应合成法制备的AgSnOz电接触材料较传统粉末冶金法制备的AgSnO2电接触材料具有更高的导电性和抗熔蚀性；该方法制备的AgSnO2电接触材料由于改变了Ag、SnO2的结合状态使材料的加工性能、导电性能和抗熔蚀性同时得到改善和提高。     

电子电气设备中塑料阻燃剂PBDE使用的危害性

多溴联苯醚(PBDE)广泛用作电子电气设备（EEE）产品中塑料件的阻燃剂,欧盟《WEEE指令》和《RoHS指令》的公布唤醒了世界各国对PBDE危害性的极大关注,本文在国内外多溴联苯醚(PBDE)危害性研究成果的基础上,介绍了电子电气设备(EEE)中多溴联苯醚(PBDE）使用的危害性。     

智能电器中的电磁兼容及其对策

基于对智能电器中的电磁兼容分析,提出了一些相应的对策.介绍了吸收回路、滤波电路、屏蔽技术、隔离技术和抗干扰设计等电磁兼容对策.这些技术手段可有效保护智能电器免受非线性负荷、雷击和浪涌的危害,提高电器可靠性.     

EIB现场总线技术在广场照明工程中的应用和设计

介绍了EIB现场总线技术和EIB系统运行软件设计和硬件要求,根据广场照明工程的特点,叙述了如何运用EIB现场总线技术,实现对广场照明的灵活控制.     

化水系统EDI工艺与混床工艺的比较及应用

介绍了化水系统中的新型EDI工艺与传统混床工艺,着重分析两者间的相同性及差异性,比较其优劣及应用,从而验证EDI工艺在今后必将取代传统混床工艺,被广泛应用于电子、电力、生物、制药、化工等诸多领域。     

甲烷在SOFC阳极中反应的条件和规律

以8%mol Y2O3稳定的ZrO2(8YSZ)为电解质、Ni-8YSZ为阳极,研究了不同电流密度、甲烷浓度和反应温度下,甲烷在固体氧化物燃料电池(SOFC)中由部分氧化到完全氧化转变的规律。在1 000℃下、甲烷浓度为4.2%时,由部分氧化转变为完全氧化的临界电流密度为0.384~0.512 A/cm2,该值与甲烷浓度及温度成正比。     

功率因数校正Boost变换器中慢时标分岔的影响因素分析与分岔控制

由于开关非线性,功率因数校正(power factor correction,PFC)Boost变换器中会出现工频周期尺度上的分岔,即慢时标分岔。首先分析所有影响慢时标分岔的因素,并揭示其影响规律;然后引入负载电流前馈方法,使PFC变换器在远离饱和区工作,实现对慢时标分岔的控制;最后,实验验证了理论分析和仿真的结果。研究结果有助于更好地理解PFC变换器中的慢时标分岔,对PFC变换器的设计也有一定的参考价值。     

MCR型SVC在轧钢供电系统中的仿真与应用

针对某轧钢厂10 kV母线的电能质量治理问题,将MCR型静止型动态无功补偿器(SVC)应用于该厂供电系统的改造。介绍了MCR型SVC的工作原理及特点,根据该厂10 kV母线的实际负荷情况,利用Matlab/Simulink仿真软件,搭建MCR型SVC仿真模型并进行仿真设计。实测数据表明,MCR型SVC在10 kV轧钢供电系统中能够有效地提高功率因数、抑制谐波,说明所采用的工程设计结合仿真分析的方法取得了良好的效果。     

PEMFC水含量的在线表征及暂态过程分析

采用电流线性扫描的方法,研究了暂态条件下PEMFC内氧还原反应(ORR)生成水量对电池性能的影响。利用微探针方法探讨了不同操作条件下燃料电池中膜内水含量的变化情况。结合电化学交流阻抗技术以及相关经验公式,分析了暂态条件下燃料电池MEA内水的扩散特性。结果表明,暂态过程中电流与电压之间的响应在秒级以内,而燃料电池的高频阻抗(HFR)变化相对于电流存在着明显的滞后现象(对于Nafion212在15～20s)。此外,还就燃料电池的吹扫操作进行了探讨研究,并对实验结果进行了理论分析和解释。     

可控串补中基频等效阻抗与电抗的关系

在动模实验的基础上,研究了可控串补（TCSC）基频等效阻抗与其可控电抗（TCR）回路基频电抗（XL）的关系。分析了XL的大小对TCSC谐振点和控制范围的影响,确定了等效基频容抗XC与电抗XL的比值关系及选择范围。