Elaboration and electrical characterization of ZnO-based varistor ceramics in different sintering temperatures

The method applied in this study to develop conventional sintered varistors is based on liquid synthesis, The percentage of raw materials used is as follows: 98 mol% ZnO, 0.5 mol% Bi₂O₃, 0.5 mol% Sb₂O₃, 0.5 mol% Co₂O₃, 0.5 mol% MnO₂ was sintered in a sintering temperature cycle from 900 to 1200 °C with different sintering times up to 120 min, the highest densification rates, 98.56%, are obtained at the temperature of 1200 °C, the grain sizes are greater than 1.61 µm for the temperature of 900 °C and increase little from one sample to another for all sintering temperatures. The presence of a spinel phase Zn₇Sb₂O₁₂ as well as Bi₂O₃. The nonlinearity coefficient was high for the majority of sintered varistors at temperatures of 1000 °C and 1100 °C such that α > 35. The trigger field values (Ea) are nearly identical for all sintering temperatures, The electric fields for sintering at 1000 °C are a little high at about 373 V.mm⁻¹ as a maximum value, 263 V.mm⁻¹ for sintering at 1100 °C and 258 V. mm⁻¹ for sintering at 1200 °C and we can also note that the density value of the leakage current is very low.