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Improved Direct-Current Aging Stability and Suppressed Leakage Current of Zinc Oxide Varistors by Co-doping with Boron, Gallium, and Yttrium

Kuan Cheng, Weiqing Wang, Dongji Liu, Qingyun Xie, Yuanxiang Zhou, Hongfeng Zhao

Journal of Ceramic Science and Technology, Vol. 11, No. 2 (2020), pp. 111-116

DOI: 10.4416/JCST2020-00008

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Abstract

The effect of B3+, Ga3+ and Y3+ co-doping on the microscopic and electrical properties of ZnO varistors is studied. Co-doping with multiple ions greatly improves the comprehensive performance of the ZnO varistors. The doped Ga3+ increases the acceptor concentration, raises the barrier height, and inhibits the increase of leakage current. Y3+ increases the voltage gradient by limiting the growth of grains. B3+ improves the resistance of ZnO varistors to direct-current aging. The varistor with a B3+ content of 0.2 mol% achieves a voltage gradient of 450 V/mm, leakage current of 0.54 A/cm2, and a nonlinear coefficient of 79. Accelerated aging experiments carried out for 1 000 h at 0.9 U1mA and 115 °C give an aging coefficient of 0.027. This research illustrates the ability of cation co-doping to improve the protection effect of metal oxide arrestors and the stability of power systems that operate at ± 1100 kV.

Keywords

Ceramic, varistor, electrical properties, DC aging, aging coefficient

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