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研究工作是在用径流喷射法形成的ZnO/Bi_2O_3双层复合试样上进行的,该试样被看作是ZnO压敏电阻中单个晶粒边界的模型。研究的目的是为了弄清楚劣化和非线性导电特性的机理,并由此了解薄片压敏电阻的性能。作者测试了试样的I—V特性曲线和热激发电流(TSC)。在反向偏压作用下,双层复合试样呈现出比实际的压敏电阻更高的非线性系数。 ZnO/Bi_2O_3双层复合试样的击穿电压随Bi_2O_3的厚度增加而增大,因此,可以由此来控制试样的击穿电压。该现象解释如下:由于Bi_2O_3体内和ZnO/Bi_2O_3交界面上电荷的积聚,增大了交界面上的电场强度。在反向偏压作用下,当温度低于120℃时,TSC按去极化方向流动;而当温度高于120℃时,TSC则按极化方向流动。该现象也可用Bi_2O_3体内以及它与ZnO交界面处的空间电荷积聚现象来解释。
The research work was carried out on the ZnO / Bi_2O_3 double layer composite formed by radial jet method, which is regarded as a model of single grain boundary in ZnO varistor. The purpose of the study was to clarify the mechanism of deterioration and non-linear conductivity characteristics and to understand the properties of the sheet varistors. The authors tested the I-V characteristic curve and thermal excitation current (TSC) of the samples. Under reverse bias, the double-layer composite exhibits a higher nonlinear coefficient than the actual varistor. The breakdown voltage of ZnO / Bi_2O_3 composite samples increases with the thickness of Bi_2O_3, therefore, the breakdown voltage of the samples can be controlled. This phenomenon is explained as follows: Due to the accumulation of charge on the interface of Bi_2O_3 and ZnO / Bi_2O_3, the electric field intensity at the interface is increased. Under reverse bias, the TSC flows in the direction of depolarization at temperatures below 120 ° C whereas the TSC flows in the direction of polarization at temperatures above 120 ° C. This phenomenon can also be explained by the phenomenon of space charge accumulation in the body of Bi 2 O 3 and its interface with ZnO.