Effect of Ni₂O₃ Doping on the Electrical Properties and Intrinsic Defect Concentration of ZnO Varistor Ceramics

State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong Universaity, Xi’an, Shaanxi Province, 710049, China

^* Corresponding author’s e-mail: sli@mail.xjtu.edu.cn

Abstract

With the development of high voltage transmission, there is an urgent need to develop ZnO varistor ceramics with high anti-aging properties. The key is to manipulate the intrinsic defect concentration of ZnO varistor ceramics precisely. In this paper, ZnO varistor ceramics doped with different contents of Ni₂O₃ are taken to study the relationship between the microstructure and electrical properties, and the effect of ZnO varistor ceramics doped with different contents on intrinsic defect concentration is also considered. The results show that, best electrical performance is shown when the content of Ni₂O₃ is 1.2mol%, the electrical breakdown field E_1mA is 356 V/mm, the nonlinear coefficient reaches 32, and the leakage current I_L is 3.4 . While the amount of the doped Ni₂O₃ is more 0.8mol%, a new phase of Co₂Cr₅Sb₅O₄ phase is observed from X-ray diffraction. The SEM micrographs showed that the average grain size decreased monotonously from 14.56 m to 5.73 m with the amount of the doped Ni₂O₃ increased. According to the results of dielectric spectroscopy, the intrinsic defect concentration increased with the contents of the doped Ni₂O₃ increased. The increase of Zinc interstitial is much greater than that of Oxygen vacancies, which is harmful to Long-term aging characteristics of ZnO varistor ceramics.