Low breakdown electric field B2O3–doped ZnO–Bi2O3–TiO2–Co2O3–MnO2 varistor ceramics fabricated by low temperature sintering

Low breakdown electric field ZnO–Bi2O3–TiO2–Co2O3–MnO2 (ZBTCM) varistor ceramics doped with various amounts of B2O3 were prepared by the solid-state reactions. The sintering temperature was 900 °C, lower than the melting point of pure silver. The microstructural features and electrical properties were investigated by XRD, SEM and a capacitance meter. The results show that B2O3 is not only a sintering additive, but also an electrical property improver. ZBTCM based varistors with breakdown field of 131.25 V/mm, nonlinear coefficient (α) of 39.13 and leakage current density (JL) lower than 2.5 µA/mm2 were obtained by doping 1 wt% B2O3 sintered at 900 °C.