Effect of dopant (Al, Nb, Bi, La) on varistor properties of ZnO–V2O5–MnO2–Co3O4–Dy2O3 ceramics

The electrical, dielectric properties, and aging behavior of ZnO–V2O5–MnO2–Co3O4–Dy2O3 (ZVMCD) ceramics were investigated with different dopants (Al, Nb, Bi, La). The phase formed for all the samples consisted of ZnO grain as a main phase, and Zn3(VO4)2, ZnV2O4, and DyVO4 as the secondary phases. On one hand, Nb and Bi dopants enhanced the nonlinear coefficient whereas Al and La dopants decreased it. On the other hand, Nb and Al improved the stability against aging stress. The Nb-doped ZVMCD ceramics exhibited the best nonlinear properties (α = 36) and the highest stability: %ΔEB = −0.4%, %Δα = −20%, %Δε′APP=−1.3%, and %Δtan δ = +13% for DC accelerated aging stress of 0.85 EB/85 °C/24 h.