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

Abstract

<jats:title>Abstract</jats:title> <jats:p>The dense ZnO-Bi<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>-MnO<jats:sub>2</jats:sub>-<jats:italic>x</jats:italic>SiO<jats:sub>2</jats:sub> (ZBMS) varistors for <jats:italic>x</jats:italic>= 0, 1, 2, 3 wt.% were fabricated by flash sintering method under the low temperature of 850 ℃ within 2 minutes. 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 SiO<jats:sub>2</jats:sub> doped content were investigated. According to the XRD analysis, many secondary phases were detected due to the SiO<jats:sub>2 </jats:sub>doping. Meanwhile, the average grain size decrease with increasing SiO<jats:sub>2</jats:sub>-doped content. The improved nonlinear characteristics were obtained in SiO<jats:sub>2</jats:sub>-doped samples, which can be attributed to the ion migration and oxygen absorption induced by the doped SiO<jats:sub>2</jats:sub>. The flash-sintered ZBMS varistor ceramics for <jats:italic>x</jats:italic>=2 wt.% exhibited excellent comprehensive electrical properties, with the nonlinear coefficient of 24.5, the threshold voltage and leakage current of 385 V×mm<jats:sup>-1</jats:sup> and 11.8 µA, respectively.</jats:p>

Fabrication of ZrO2/rGO nanocomposites by flash sintering under AC electric fields

“…Many works have proved that the current limit has a great influence on the densification in the flash sintering. Low current limit leads to the low density of flash‐sintered samples 43–46 . In this work, because the current limit is controlled by a constant resistor of 500 Ω, the higher electric field results in the higher current limit, thus leading to the higher density of the flash‐sintered sample, which is confirmed by the density measurements and SEM results (Figure 5).…”