Effects of SiO2/Cr2O3 ratios on microstructures and electrical properties of high voltage gradient ZnO varistors

• Published in: Journal of materials science. Materials in electronics 2019-07, Vol.30 (13), p.12113-12121
• Main Authors: Ruan, Xuejun, Ren, Xin, Zhou, Wenting, Xu, Xi, Wang, Xin, Wang, Manyu, Yan, Ying, Yao, Zheng, Shi, Wen, Yu, Wenqi
• Format: Article
• Language: English
• Subjects: Aging; Characterization and Evaluation of Materials; Chemistry and Materials Science; Chromium oxides; Electric potential; Electric power distribution; Electrical properties; Electronic devices; Grain boundaries; Grain growth; Grain size; High voltages; Industrial applications; Leakage current; Materials Science; Metal oxides; Optical and Electronic Materials; Polyvinyl alcohol; Silicon dioxide; Sintering; Square waves; Varistors; Wave power; Zinc oxide; Zinc oxides
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-019-01569-6

The effect of various proportions of SiO 2 and Cr 2 O 3 doping on the micro-characteristics and the electrical properties of the ZnO varistors were investigated. As the SiO 2 /Cr 2 O 3 ratio increased, the voltage gradient increased and then decreased, the nonlinear coefficient α increased, while the leakage current showed the opposite trend, meanwhile the residual voltage ratio was almost stable. When the SiO 2 /Cr 2 O 3 ratio was 1.7 mol% vs. 0.6 mol%, the ZnO varistors sintered at 1155 °C exhibited excellent comprehensive electrical properties with voltage gradient of 329.9 V/mm, nonlinear coefficient of 65.1, leakage current of 0 µA, residual voltage ratio of 1.663, and aging starting power of 0.72 W. The varistors were in good condition after being struck 18 times of 250 A square wave energy pulse impact, showing a great potential in the industrial application of power distribution systems.