The effect of SiO2on electrical properties of low‐temperature‐sintered ZnO–Bi2O3–TiO2–Co2O3–MnO2‐based ceramics

Abstract

AbstractZnO–Bi2O3–TiO2–Co2O3–MnO2‐based (ZBTCM) varistors were fabricated via the conventional solid‐state method, and the effect of SiO2content on the phase transformation, microstructure, and electrical properties of theZBTCMhad been investigated. Results showed that this varistor can be sintered at a low temperature of 880°C with a high sintering density above 0.95 of the ZnO theoretical density. In these components, SiO2acts as a controller in ZnO grain growth, decreasing the grain size of ZnO from 3.67 to 1.92 μm, which in turn results in an increase in breakdown voltageE1mAfrom 358.11 to 1080 V/mm. On the other hand, SiO2has a significant influence on the defect structure and component distribution at grain‐boundary regions. When SiO2content increases from 0 to 4 wt%, the value of the interface state density (Ns) increases sharply. At the same time, the electrical properties are improved gradually, and reach an optimized value with the nonlinear coefficient (α) up to 54.18, the barrier height (ϕb) up to 2.90 eV, and the leakage current (IL) down to 0.193 μA/cm2.