The microstructure, electrical properties, dielectric characteristics, and DC accelerated aging behavior of the MnCoDy modified Zn–V-based varistors were investigated for Nb amount of 0.0–0.25 mol% by sintering at 900 °C. The microstructure of the MnCoDy modified Zn–V-based varistors consisted of ZnO grain as a main phase and Zn3(VO4)2, ZnV2O4, and DyVO4 as the secondary phases. The Nb addition led to the increase of grain size, whereas it does not have an effect on the sintered density. The nonlinear coefficient improved with the increase of Nb amount up to 0.1 mol%, whereas the further Nb additions impaired it. A maximum of the nonlinear coefficient (35) was obtained at 0.1 mol% Nb. The Nb acted as a donor less than 0.1 mol% and an acceptor more than 0.25 mol%. The best stability of system against DC accelerated aging stress was obtained at 0.1 mol% Nb, in which %ΔE1 mA = −0.24%, %Δα = −15.4%, %Δ ε′APP = −1.4%, and %Δ tanδ = +12.5% for stress state of 0.85 E1 mA/85 °C/24 h.
Barrier Height Schottky Barrier Leakage Current Density Nonlinear Coefficient Sintered Density
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