Fabrication and electrical characteristics of flash-sintered SiO2-doped ZnO-Bi2O3-MnO2 varistors

Abstract

The dense ZnO-Bi 2 O 3 -MnO 2 - x SiO 2 (ZBMS) varistors were fabricated by flash sintering method under the low temperature of 850 o C within 2 minutes. The phase structure, density, microstructure, and electrical characteristics of the flash-sintered ZBMS varistors with different SiO 2 doping content were investigated. According to the XRD analysis, many secondary phases were detected due to the doping of SiO 2 . Meanwhile, the average grain size decrease with increasing SiO 2 doping content. In addition, the electrical properties of all samples were analyzed. The improved nonlinear characteristics were obtained in SiO 2 doped samples, which can be attributed to the ion migration and oxygen absorption induced by the doping of SiO 2 . The flash-sintered ZBMS varistor ceramics exhibited excellent comprehensive electrical properties, with the nonlinear coefficient of 24.5, the threshold voltage and leakage current of 385 V/mm and 11.8 µA, respectively.