Abstract
The dense ZnO-Bi2O3-MnO2-xSiO2 (ZBMS) varistors for x = 0, 1, 2, 3 wt% were fabricated by flash sintering method under the low temperature of 850 °C within 2 min. The sample temperature was estimated by a black body radiation model in the flash sintering process. The crystalline phase assemblage, density, microstructure, and electrical characteristics of the flash-sintered ZBMS varistors with different SiO2-doped content were investigated. According to the XRD analysis, many secondary phases were detected due to the SiO2 doping. Meanwhile, the average grain size decrease with increasing SiO2-doped content. The improved nonlinear characteristics were obtained in SiO2-doped samples, which can be attributed to the ion migration and oxygen absorption induced by the doped SiO2. The flash-sintered ZBMS varistor ceramics for x = 2 wt% exhibited excellent comprehensive electrical properties, with the nonlinear coefficient of 24.5, the threshold voltage and leakage current of 385 V·mm−1 and 11.8 µA, respectively.
Highlights
IntroductionJ Adv Ceram 2020, 9(6): 683–692 volatilization of some elements (like Bi), which in turn affects the varistor properties
ZnO varistors have been successfully applied to the surge protector in electrical transmission and transient overvoltage or circuits to prevent lightning strikes due to their excellent nonlinearly electrical characteristicsJ Adv Ceram 2020, 9(6): 683–692 volatilization of some elements, which in turn affects the varistor properties
The power density curve had the same trend as the variations of current and voltage because the power density is the combination of the voltage and current
Summary
J Adv Ceram 2020, 9(6): 683–692 volatilization of some elements (like Bi), which in turn affects the varistor properties. Based on the above discussion, ZnO varistors can be prepared by the flash sintering method. Zhang and Luo [26] prepared ZnO specimen by flash sintering method at low furnace temperature (< 120 °C). The research mainly focuses on the flash sintering of pure zinc oxide, and there are few investigations on the ZnO-based varistor. ZnO–Bi2O3–MnO2 varistors have been fabricated by the flash sintering at a very low sintering temperature of 768–702 °C under an electric field of 200–400 V cm–1, which showed an excellent nonlinear property [35]. According to the above discussions, it is very meaningful to explore the effect of different SiO2 content on the structure and electrical properties of ZnO–Bi2O3–MnO2-based varistor prepared by flash sintering. The specimen temperature was estimated by the black body radiation model during the flash event
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