DC Aging Mechanism of Co 2 O 3 -Doped ZnO Varistors

Xia Zhao, Haibin Shen, Men Guo, Ziming He, Yupeng Li and Ran Wen
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Xia Zhao: China Electric Power Research Institute, Beijing 100192, China
Haibin Shen: China Electric Power Research Institute, Beijing 100192, China
Men Guo: State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710049, China
Ziming He: China Electric Power Research Institute, Beijing 100192, China
Yupeng Li: State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University, Chongqing 400044, China
Ran Wen: School of Electronics and Information, Xian Polytechnic University, Xi’an 710048, China

Energies, 2021, vol. 14, issue 13, 1-12

Abstract: Lowered power loss and asymmetrically electrical parameters are reported in the DC aging of Co 2 O 3 -doped ZnO varistors in this paper. Based on the frequency domain dielectric responses of the pristine and degraded samples, the present study explores the roles of point defects in the aging process via dielectric relaxations and their parameters. It is found that breakdown field increased more in the positive direction than the negative direction. Nonlinearity increased in the positive direction, whereas it decreased in the negative direction, and leakage current density increased more in the negative direction than the positive direction. Given the lowest migration energy of Zinc interstitial (Zn i , 0.57 eV) and high oxygen ion conductivity in Bi 2 O 3 -rich phase, it is speculated that Zni and adsorbed oxygen (O ad ) migrate under DC bias, and then change the defect structure and the double Schottky barrier (DSB) at grain boundaries. As a result, the forward-biased barrier height gradually decreases more than the reverse-biased one.

Keywords: ZnO varistors; DC aging; double Schottky barrier; point defects (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2021
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