Preparation and varistor properties of new quaternary Zn–V–Mn–(La, Dy) ceramics

The La and Dy doping effects on microstructures, nonlinear electrical properties, and its stability of ZVM (Zn–V–Mn)-based ceramics were investigated. The microstructure of the quaternary ZVML (Zn–V–Mn–La)-based ceramics doped with La and quaternary ZVMD (Zn–V–Mn–Dy)-based ceramics doped with Dy commonly consisted of mainly ZnO grains and Zn3(VO4)2 as a secondary phase. In addition, the quaternary ZVML- and ZVMD-based ceramics revealed the secondary phases, such as LaVO4 and DyVO4, respectively, in addition to Zn3(VO4)2. It seems that all secondary phases act as a liquid-phase sintering aid because it has a significant effect on the sintered density and average grain size. The incorporation of La and Dy into the ZVM-based ceramics increased the breakdown field, and improved the nonlinear electrical properties, in which the nonlinear coefficient was close to 33. The ZVML-based ceramics exhibited the best stability, where the variation of breakdown field (%ΔEB) against DC accelerated aging stress is −9.7%.