This study introduces a new investigation report on the microstructural and electrical property changes of ZnO-Zn2BiVO6-Mn3O4 (ZZMn), where 0.33 mol% of Mn3O4 and 0.5 mol% of Zn2BiVO6 were added to ZnO (99.17 mol%) as liquid phase sintering aids. Zn2BiVO6 contributes to the decrease of sintering temperatures by up to 800℃, and segregates its particles at the grain boundary, while Mn3O4 enhances α, the nonlinear coefficient, of varistor properties up to α＝62. In comparison, when the sintering temperature is increased from 800℃ to 1,000℃, the resistivity of ZnO grains decreases from 0.34 Ωcm to 0.16 Ωcm, and the varistor property degrades. Oxygen vacancy (Vo·) (P1, 0.33~0.36 eV) is formed as a dominant defect. Two different kinds of grain boundary activation energies of P2 (0.51~0.70 eV) and P3 (0.70~0.93 eV) are formed according to different sintering temperatures, which are tentatively attributed to be ZnO/Zn2BiVO6-rich interface and ZnO/ZnO interface, respectively. Accordingly, this study introduces a progressive method of manufacturing ZnO chip varistors by way of sintering ZZMn-based varistor under 900℃. However, to procure a higher reliability, an in-depth study on the multi-component varistors with double-layer grain boundaries should be executed.
