The effect of SiO2 on electrical properties of low‐temperature‐sintered ZnO–Bi2O3–TiO2–Co2O3–MnO2‐based ceramics

Abstract ZnO–Bi 2 O 3 –TiO 2 –Co 2 O 3 –MnO 2 ‐based ( ZBTCM ) varistors were fabricated via the conventional solid‐state method, and the effect of SiO 2 content on the phase transformation, microstructure, and electrical properties of the ZBTCM had 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, SiO 2 acts 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 voltage E 1mA from 358.11 to 1080 V/mm. On the other hand, SiO 2 has a significant influence on the defect structure and component distribution at grain‐boundary regions. When SiO 2 content increases from 0 to 4 wt%, the value of the interface state density ( N s ) 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 (ϕ b ) up to 2.90 eV, and the leakage current ( I L ) down to 0.193 μA/cm 2 .