Abstract:The effect of small changes in sintering temperature on microstructure, electrical properties, dielectric characteristics, and degradation behavior of V-Mn-Nb-Gd co-doped zinc oxide ceramics was investigated. With the increase of sintering temperature, the densities of the sintered pellets decreased from 5.54 to 5.42 g/cm³ and the average grain size increased from 4.1 to 11.7 mm. The breakdown field (E_{1 mA}) decreased noticeably from 7138 to 920 V/cm with the increase of sintering temperature. The varistor ceramics sintered at 900 °C exhibited excellent nonohmic properties, which were 66 for the nonohmic coefficient and 77 mA/cm² for the leakage current density. Concerning stability, the varistors sintered at 900 °C exhibited the strongest accelerated degradation characteristics, with ΔE_{1 mA} =-9.2% for DC accelerated degradation stress of 0.85 E_{1 mA} at 85 °C for 24 h.

Key words: ZnO-V₂O₅-based ceramics; sintering; electrical properties; degradation behavior; varistor