Improvement of electrical properties of V2O5 modified ZnO ceramics by Mn-doping for varistor applications
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The dependence of microstructure, electrical properties, dielectric characteristics, and stability of conduction characteristics in ternary ZnO–V2O5–Mn3O4 system on the amount of Mn3O4 present in them was investigated. For all compositions studied, the microstructure of the ternary ZnO–V2O5–Mn3O4 system consisted of mainly ZnO grains and Zn3(VO4)2 as a secondary phase. The incorporation of Mn3O4 to the binary ZnO–V2O5 system was found to restrict abnormal grain growth of ZnO. The breakdown field in the electric field–current density characteristics increased from 175 to 4,635 V/cm with the increase of Mn3O4 amount. The ternary system doped with 0.5 mol% Mn3O4 exhibited the highest non-ohmic properties, in which the non-ohmic coefficient is 22.4 and the leakage current density is 0.22 mA/cm2. Furthermore, the sample doped with 0.5 mol% Mn3O4 was found to possess 0.43 × 1018/cm3 in donor density and 2.66 eV in barrier height.
KeywordsElectroceramics Vanadium Microstructure Electrical properties Varistors
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