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Studies on the Composition-Structure-Property Relations in Ceramic Grain-Boundaries

陶瓷晶界成分-结构-性能关系的研究

基本信息

批准号：
60550543
负责人：
KOUMOTO Kunihito
金额：
$ 1.28万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1985
资助国家：
日本
起止时间：
1985 至 1986
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-60550543/
关键词：
Grain Boundary Ceramics Humidity-Sensing Electrical breakdown Diffusion I-V Characteristics バリスタ

项目摘要

TEM observations of the grain boundary areas were made on semiconductng <BaTiO_3> Thick film. The 180 domains across the grain boundary could not be ovserved the possibility of the existence of 90 domains was suggested. Exsolution method was applied to the NiO-ZnO ceramics to control the microstructure in which the grain-boundary regions were rich in ZnO and the grains were NiO rich phase, as detected by XMA. The change in V-I characteristics with the change in relative humidity was measured at 25゜c. <Ni_(0.2)Zn_(0.8)O> sintered at 1300゜c and further annealed at 800゜c for 336h was found to be the most sensitive to humidity. The electrical breakdown strength of single crystal MgO at 1000-1400゜c decreased with increase in the dislocation density and that of polycrystalline MgO indicated a significant effect of the grain boundaries. A high correlation between the ionic conductivity and the breakdown strength was found, which together with the observed melted track suggested that the electrolytic decomposition took place. The varistor properties were examined for porous ZnO containing no dopants such as <Bi_2O_3> or <Pr_6O_(11)> . Comparison of I-V curves for the oxidized and unoxidized samples indicated that oxygen, which had chemisorbed and diffused into the grain boundary, played a role in giving rise to varistor characteristics.

用透射电镜观察了厚膜的晶界区<BaTiO_3>。晶界上的180个畴不能被观察到，提出了90个畴存在的可能性。采用出溶法对NiO-ZnO陶瓷进行了控制，通过XMA分析发现，陶瓷的晶界区域富含ZnO，晶粒为富NiO相。在25 ℃下测量V-I特性随相对湿度变化的变化。在1300 ℃烧结并在800 ℃进一步退火336小时的<Ni_（0.2）Zn_（0.8）O>对湿度最敏感。单晶MgO在1000-1400 ℃的电击穿强度随位错密度的增加而降低，而多晶MgO的电击穿强度受晶界的影响较大。离子电导率和击穿强度之间的高度相关性被发现，这与所观察到的熔融轨迹一起表明发生了电解分解。研究了不含<Bi_2O_3>Pr_6O_（11）或<Pr_6O_（11）>等掺杂剂的多孔ZnO的压敏性能。氧化和未氧化的样品的I-V曲线的比较表明，氧，化学吸附和扩散到晶界，起到了提高压敏电阻特性的作用。