Effect of sintering temperature on microstructure and varistor properties of Zn-V-O-based ceramics incorporated with Mn-Nb-Tb

The effect of sintering temperature on microstructure and varistor properties of Zn-V-O-based ceramics incorporated with Mn-Nb-Tb was investigated. The results showed that the increase of sintering temperature in the range from 875 to 950 °C decreased the densities of sintered pellets in the range of 5.55 to 5.45 g/cm3 and increased the average grain size in the range of 4.1 to 8.8 μm. The breakdown field decreased noticeably from 7443 to 1064 V/cm with increasing sintering temperature from 875 to 950 °C. The varistor ceramics sintered at 900 °C exhibited nonlinear properties, with 49.4 in the nonlinear coefficient and 0.21 mA/cm2 in the leakage current density. The dielectric constant increased greatly from 440.1 to 2197.2 with increasing sintering temperature from 875 to 950 °C; however, the dissipation factor exhibited a fluctuation between 0.237 and 0.5. These ceramic compositions and sintering conditions can be applied to the development of advanced multiplayer varistors with silver as an inner electrode.