陶瓷与有机PTC热敏电阻高频特性研究

简述了陶瓷PTC热敏电阻和有机PTC热敏电阻的特性，介绍了2类PTC热敏电阻的PTC效应原理，并就2类PTC热敏电阻高频特性结合试验测量结果进行了分析，陶瓷PTCR采用的测试信号频率为10kHz-10MHz，有机PTCR所采用的测试信号频率为10kHz-6GHz，结果表明有机PTCR较陶瓷PTCR有良好的高频过流保护特性，这说明有机PTCR更适合用于高频过流保护。     

用扩展电阻法研究陶瓷微区电导性能

本文把扩展电阻法应用于陶瓷微区电导性能研究.建立了微区的定位标识系统,可精确、方便地对选定的微区进行电导性能及组分的重复测定.该方法在研究Ba(Sn_(1-x)Sb_x)O_3、ZnO及BaTiO_3半导体瓷应用中得到有意义的结果.     

Sr(Fe_(1-x)Ti_x)O_(3-δ)系陶瓷电导特性的研究

本文借助穆斯堡尔谱学研究了大气烧成条件下Sr(Fe_(1-x)Ti_x)O_(3-δ)系陶瓷材料的电导和电导温度特性,揭示了电导与氧缺位、Fe~(4+)含量的关系。研究发现,SrFeO_(3-δ)系陶瓷中存在过去未知的Fe_((π))~(3+)。     

锰镍复合氧化物半导体纳米陶瓷的微观结构和电性能研究

对用溶胶一凝胶(SOL—GEL)工艺制备出的纳米粉末进行加压、烧结处理,制成NiO/Mn_3O_4.复合氧化物半导体纳米陶瓷试样,通过XRD、SEM、复阻抗和电导特性对复合氧化物样品的结构和电性能进行分析研究,结果表明纳米陶瓷电学特性与其显微结构有着十分密切关系.     

陶瓷热敏电阻氢处理降阻的研究

陶瓷热敏电阻氢处理降阻的研究樊玉薇，贾连娣，吴冲若（东南大学电子工程系，南京２１００１８）为使钛酸钡系陶瓷正温度系数热敏电阻（ＰＴＣＲ）的电阻率在一定范围内，一般方法是通过控制原材料纯度、微量元素分布均匀性与工艺过程一致性来减小阻值分散［１］，而对烧...     

一种新的固相反应法制备高掺杂浓度的CaCu_3Ti_4O_(12)陶瓷

采用新的两步固相反应法,制备单相(Fe1/2Nb1/2)4+掺杂CaCu_3Ti_4O_(12)陶瓷,掺杂浓度在50 mol%到60 mol%之间,观察粉末X射线衍射谱,没有发现任何杂相.探索样品的最佳烧成制度,制备出致密性高的陶瓷.分析样品的阻抗特性,发现样品存在与晶界有关的热激活电导响应,随着(Fe1/2Nb1/2)4+掺杂浓度增加,晶界的电导激活能增加.进一步探究发现,晶界的电导响应可能与直流电导过程相关.这里采用新的两步固相反应法,成功地制备出了(Fe1/2Nb1/2)4+高浓度掺杂的单相CaCu_3Ti_4O_(12)样品,为今后研究(B1-xB′x)4+形式的复合离子高水平地替代CaCu_3Ti_4O_(12)中的Ti4+提供了制备方法上的新思路.     

钛酸钡PTC热敏电阻陶瓷表面态浅析

就形成钛酸钡陶瓷PTC效应的表面态进行阐述,分析了在居里点(TC)以上由表面态和介电常数在共同作用下的电阻率猛增几个数量级的原因;同时对钛酸钡PTC热敏电阻陶瓷的表面态的组成进行研究,认为在钛酸钡PTC陶瓷中表面态主要由钡空位引起;提出一种直接测量表面态密度的方法.     

LaMO_3-AB_2O_4复合陶瓷材料及其复合机制的研究

研究了钙钛矿型 (ABO3 )陶瓷与尖晶石型 (AB2 O4 )陶瓷材料的复合机制 ,实验发现 :钙钛矿型陶瓷与尖晶石型陶瓷材料以一定的比例进行复合 ,在高温烧结过程中有离子迁移发生 ,离子迁移主要在B位间进行 .复合体电导率与离子迁移后所形成的结构状态有关 ,当复合体产生高电导结构时 ,复合体电阻率降低 ,反之 ,电阻率增高 .     

固相法制备细晶高性能PTCR

针对正温度系数热敏电阻(PTCR)片式化技术对陶瓷晶粒尺寸提出的较高要求,利用固相法制备PTCR,结合提高施受主掺杂比(n(Y∶Mn)21效果明显),高温预烧(1 220℃),低温烧结(1 300℃)等方法抑制晶粒长大;制备出平均晶粒尺寸小于2μm,室温电阻率为205Ω.cm,升阻比为4.082×104的BaTiO3基多层片式细晶PTC陶瓷,使多层片式PTCR产业化成为现实.     

CaCu3Ti4O12的制备及电导研究

按CaCu3Ti4O12的组分进行化学配比，经850℃-955℃预烧、900℃-1100℃烧结6 h，成功制备了CaCu3Ti4O12粉体前驱体和CaCu3Ti4O12巨介电常数陶瓷材料.用X射线衍射仪、扫描电镜（SEM）对体系进行了结晶性能和形貌观察.用阻抗分析仪在25 K-355 K温区范围内测定了陶瓷样品的介电性能和电导.结果表明：955℃预烧的粉体在1060℃温度下只需烧结6 h，陶瓷样品的介电值在10 kHz频率下，在100 K-355 K范围内可高达2.0×10^5，与文献报道的相比，其介电性能最好且烧结时间最短；电导与温度及频率的关系是由电子、声子与外场的共同作用决定的.     

电致发热SiC多孔陶瓷导电性能研究

研究了Al，B和Zr元素对电致发热多孔碳化硅陶瓷导电性的影响。室温电阻率测定表明，加入Al，B和Zr都可显著降低电致发热多孔碳化硅陶瓷的电阻率，随着Al，B和Zr加入量的增加，试样的室温电阻率下降。讨论了Al，B和Zr在碳化硅中的存在形式，并分析了试样的导电机理。     

BaPbO3与BaTiO3陶瓷的导电特性比较

从BaPbO3与BaTiO3多晶态陶瓷的缺陷结构出发,结合不同气氛下烧成试样的室温电导率,探讨两种材料的导电特性与晶体缺陷结构之间的关系,从微观本质上阐述晶体缺陷对材料电学性能的影响.结果表明:BaPbO3与BaTiO3不同的缺陷结构决定了两种材料具有不同的电学性能;BaPbO3材料中受主能级较浅,受主中心所束缚的空穴很容易跃迁至价带形成导电载流子,在氧化气氛下烧成的试样呈高导电性;BaTiO3材料中受主能级较深,氧化气氛下烧成的试样为绝缘体.     

BaTi1-xFexO3-δ六方钙钛矿陶瓷材料的NTC特性

采用湿化学合成方法制备BaTi1-xFexO3-δ(x=0.1,0.2.0.3)粉体,经传统烧结工艺得到致密的块体陶瓷材料.利用X线衍射分析材料的相组成,通过电阻-温度特性和交流阻抗谱分析材料的导电性质随温度变化的特性.利用热激活诱导极化子跳跃导电模型对材料的NTC特性进行分析讨论.研究结果表明:BaTi1-xFexO3-δ材料具有六方钙钛矿晶体结构,并体现出优异的电阻负温度系数(NTC)特性;当x=0.1,0.2和0.3时,BaTi1-xFexO3-δ的NTC系数分别为5497,5284和4828K.     

Abnormal thermal shock behavior in electrical conductivity of Ti2SnC

Some ternary carbide and nitride ceramics have been demonstrated to exhibit abnormal thermal shock behavior in mechanical properties. However, the influence of thermal shock on other properties is not clear. This work reports on the influence of thermal shock on electrical conductivity of Ti_2SnC as a representative member of ternary carbides. Abnormal change in electrical conductivity was first demonstrated during quenching Ti_2 SnC in water at 500-800 ℃. The residual electrical conductivity of the quenched Ti_2SnC gradually decreased with increasing temperature, but abnormally increased after quenching at 600 ℃. The microstructure of surface cracks was characterized. The main mechanism for the abnormal electrical conductivity recovery is that some narrow branching cracks are filled by metallic Sn precipitating from Ti_2SnC.     

锅炉用水中电导率与含盐量关系的研究

通过pH值、温度对电导率影响的实验研究,得出pH值在8.3时电导率与含盐量的变化及电导率与温度的变化均呈现良好的线性关系.从模拟锅炉水标准溶液的实验结果分析,得出含盐量与电导率关系的计算式为:TDS=κ×A±κ×A×B×△t.利用该式可以快速检测锅炉水的含盐量并可建立在线检测.     

Temperature characteristics of electrical behavior of W-Bi-Ti-O ceramics at low field

Bi2WTi3O12 ceramics are fabricated by the conventional solid-state reaction process. With increasing temperature the sample first has metallic behavior, then strong electrical fluctuations above 100℃, and finally exhibits stable nonlinear properties characterized by semiconductivity above 300℃ at low field (E≤100 V/mm). The Arrhenius law for electrical conductivity by thermal activation is not suitable to explain the anomalous results. XRD analysis reveals that Bi2WO6 is the main phase and Bi4Ti3O12 is the second phase. Based on the phase transition of tungsten trioxide from room temperature to about 300℃, the electrical properties of Bi2WTi3O12 ceramics can be explained.     

Thermoelectric properties of tungsten ceramics prepared from nanopowder precursors

Tungsten trioxide ceramics were prepared from nm-sized powder precursors. Thermoelectric properties of samples were investigated. The results demonstrated that ceramics prepared in this manner have improved electrical conductivity and Seebeck coefficient values. The power factor of these samples also improved markedly, the largest power factor being 0.027 μW m-1K-2 at 773 K.     

The electrical conductivity of H_2O at 0.21-4.18 GPa and 20 -350℃

The electrical conductivity of H2O in solid and liquid phases has been measured at 0.21-4.18 GPa and 20-350℃. The results indicate: ( i ) different phases of H2O in solid have different relations between electrical conductivity and temperature and pressure. The conductivity changes continuously with temperature, but discontinuously with the pressure between 2.11 and 2.58 GPa, which corresponds to the transforming pressure between ice (Ⅵ) and ice ( Ⅶ ) ; ( ii ) the con-ductivity of H2O in liquid all increases with temperature and pressure, but there are discontinuities at pressures between 0.57 and 0.9 GPa, and between 2.11 and 2.58 GPa, which are also consistent with the polymorph of ice (ice ( Ⅴ), ice (Ⅵ) and ice ( Ⅶ ) ) . This reflects that H2O in liquid at different pressures has quite different properties of electron chemistry. It is prob-ably the important reason that causes the layers with high electrical conductivity and low velocity in the earth's crust and upper mantle.     

Effect of addition of poly（ethylene glycol） on electrical conductivity of poly（3,4-ethylenedioxythiophene）-poly（styrenesulfonate） hybrid

By mixing various concentrations of poly (ethylene glycol), a series of poly(3,4-ethylenedioxythiophene)-poly(styeenesuffonate) composite thin films were prepared.The electrical conductivity of the PEDOT-PSS/PEG thin films was measured by the four-pcobe method. Experimental results showed that the inclusion of poly(ethylene glycol) influenced the electrical conductivity of PEDOT-PSS film significantly. With the increase of PEG concentrations, the electrical conductivity sharply increased to reach a maximum and then slowly decreased down. Furthermore, the PEG molecular weight and environment temperature also played important roles on the electrical conductivity of PEDOT-PSS/PEG thin films. A good linear relationship was found between in σDC and T^-1/2 within the entire temperature range detected.     

Microstructure and electrical conductivity of 10% Yb-doped SrCeO3 ceramics

As a candidate material for hydrogen separation, Yb-doped SrCeO₃ has attracted increasing attention in recent decades. In the present study, Yb-doped SrCe_0.9Yb_0.1O_3-α ceramics were prepared by the dry pressing and sintering approach, with the microstructure evolution and the micro morphology investigated. It was indicated that the ceramics sintered in air were of a pure perovskite structure, and that the sintering temperature had a significant effect on the growth of ceramic grains. The average grain size increased from 1 ​μm to 10 ​μm with an increase in sintering temperature from 1300 to 1500 ​°C. Further investigation of the thermodynamics and kinetics of grain growth revealed that the grain boundary diffusion was the main driving force of grain growth during solid phase sintering, with a grain growth index of 4 and an activation energy of approximately 61.23 ​kJ ​mol⁻¹. These results illustrate an obvious tendency of grain size growth. By electrochemical workstation with different atmospheres the effects of sintering temperature on the conductivity were characterized in the temperature range of 700–900 ​°C. The electrical conductivities σ of SrCe_0.9Yb_0.1O_3-α ceramics in different atmospheres were as follows: σ(wet hydrogen) ​> ​σ(dry hydrogen) ​> ​σ(dry air) ​> ​σ(wet air). In the test atmosphere containing water and hydrogen the conductivity of protons increased with increasing temperature because of the protons jump between lattices in the form of interstitial hydrogen ions or bare protons.