Keywords: 
• ZnO压敏陶瓷 /
• 介电谱 /
• Schottky势垒 /
• 显微结构

Abstract: In this paper, the dielectric spectra of ZnO varistor ceramics are measured by Novocontrol wide band die}eetric spectrometer in a temperature range of -160 ~C-200 ~C and frequency range of 0.1 Hz-0.1 MHz. It is found that electron transportation can be characterized by the flat region on a low frequency side of ~r'-f curve. The Schottky barrier height is 0.77 eV obtained from crl-f curve, which is consistent very well with the data from 1-V curves given in other literature. On the basis of back-to-back double Schottky barrier model, Schottky barrier height corresponding to electron transportation across grainboundary is explained to be the energy difference between interface state and barrier top. According to this explanation, Schottky barrier height will increase linearly with the increase of DC voltage applied. The linear variation of barrier height with the increase of DC voltage applied is confirmed experimentally. Finally, the theoretical value of averaged grain size is obtained to be 6.8 ~tm, which is almost identical to 6.5 Ixm measured from SEM images. Therefore, the macroscopic electrical properties and the microstructure can be expressed at the same time by dielectric spectra.