Low-temperature sintering effect on varistor properties of ZnO–V2O5–MnO2–Nb2O5–Bi2O3 ceramics

The microstructure and electrical properties of the ZnO–V2O5–MnO2–Nb2O5–Bi2O3 varistor ceramics were systematically investigated at different sintering temperatures (875–950 °C). The average grain size increased remarkably in the range of 5.4 to 15.0 μm with an increase in the sintering temperature. The sintered density of pellets decreased from 5.50 to 5.34 g/cm3 as the sintering temperature increased. The breakdown field decreased noticeably from 5785 to 1181 V/cm with an increase in the sintering temperature. The varistor ceramics sintered at 900 °C exhibited excellent nonlinear properties, in which the nonlinear coefficient is 61.5 and the leakage current density is 14.1 μA/cm2.