LIAO Jihong, ZHONG Zhicheng, CHEN Yang, QU Shaohua
(School of Physics and Electronic Engineering, Hubei University of Arts and Science, Xiangyang 441053, Hubei, China)

Abstract: The Zn-Bi varistor ceramics was prepared by solid phase method with the co-doping of 0.08mol% Y₂O₃ and x mol% ln₂O₃. The effect of the co-doping on the as-prepared varistor ceramics obtained after being sintered at 1120 °C for 3 hours was observed. The doping ratio of ln₂O₃ on the grain size, microstructure and electrical properties of ZnO ceramics were studied. The results show that, when co-doped with a small amount of Y₂O₃ and ln₂O₃, the grain size of the ZnO varistor ceramics is more uniform and finer, the microstructure is more compact, the composition and structure of grain boundary are optimized, and the nonlinear characteristics are improved. The varistor ceramic materials doped with 0.08mol% Y₂O₃ and 0.7mol% ln₂O₃ are suitable for fabricating high potential gradient arresters. The varistor voltage gradient can reach 1080 V/mm, the nonlinear coefficient is 55, and the leakage current is 0.60 μA.

Key words: ZnO varistor ceramics; Y₂O₃ and ln₂O₃ co-doping; nonlinear coefficient; high potential gradient