Microstructure and electrical characteristics of ZnO–B2O3–PbO–V2O5–MnO2 ceramics prepared from ZnO nanopowders

A peculiar kind of ZnO–B2O3–PbO–V2O5–MnO2 ceramics was produced from the ZnO nanopowders directly co-doped with the oxides instead of lead zinc borate frit in this investigation. The 8 wt.% (PbO+B2O3) co-doped ceramics sintered at 950 °C for 2 h displayed the optimum electrical properties, that is, leakage current density JL=6.2×10−6 A/cm2, nonlinear coefficient α=22.8 and breakdown voltage VBK=331 V/mm. The co-doping of 8 wt.% (PbO+B2O3) resulted in an increase in nonlinear coefficient and a decrease in leakage current density of the ZnO–V2O5 varistors while the sintering temperature showed no evident influence on nonlinear coefficient and leakage current density at the range of 800–950 °C.