ZnO压敏陶瓷介电损耗的温度谱研究

利用Novocontrol宽频介电谱仪在-100—20 ℃温度范围内测量了ZnO-Bi₂O₃系压敏陶瓷的介电频谱，其频率范围为10^-2—10⁶ Hz. 研究表明： ZnO压敏陶瓷特征损耗峰的活化能分别为0.26和0.36 eV，结合实验条件、理论计算结果及其他现象的分析排除了特征损耗峰源于阴极电子注入、夹层极化和偶极子转向极化的可能.热刺激电流（TSC）谱共出现三个峰，其中高温峰对应于TSC实验加压过程引入的热离子极化，而中温峰和低温峰对应于介电损耗峰. 在分析的基础上，提出了ZnO压敏陶瓷的特征损耗峰起源于耗尽层内本征缺陷的电子弛豫过程. 关键词： ZnO压敏陶瓷 本征缺陷 介电谱 热刺激电流

Dielectric loss of ZnO varistor ceramics by variable temperature spectroscopy

In this paper， the dielectric spectra of ZnO varistor ceramic were measured by Novocontrol wide band dielectric spectrometer in the temperature range of -100 ℃—20 ℃ and frequency range of 10^-2—10⁶ Hz. It is found that the activation energy is 0.26 and 0.36 eV， respectively. After careful analysis of the measurement conditions， quantitative calculation results and other phenomena， three relaxations of cathode electron injection， dipole polarization and interface polarization are discarded. Thermally stimulated current（TSC） has three peaks， of which the higher temperature peak comes from thermionic polarization introduced by TSC itself， and other two peaks correspond to the characteristic loss peaks in dielectric spectra. Therefore， it is concluded that the characteristic loss peaks of ZnO ceramics originate from electronic relaxation of intrinsic defects.