| Abstract |
| We prepared ZnO-Bi2O3-Sb2O3-Mn3O4-NiO(Sb/Bi=0.5, 1.0, and 2.0) varistors to examine the co-doping effect of 1/6 mol% Mn3O4 and 0.5 mol% NiO (Mn:Ni = 1:1) on the reaction, microstructure, and electrical properties, such as J-E characteristics, bulk defects and grain boundary properties. The sintering and electrical properties of the ZnO-Bi2O3-Sb2O3-Mn3O4-NiO varistor were controlled by Sb/Bi ratio. Pyrochlore (Zn2Bi3Sb3O14) was decomposed and promoted densification at lower temperature in Sb/Bi = 1.0. Pyrochlore reproduced on cooling, α-spinel (Zn7Sb2O12), and β-Bi2O3 were formed in all systems above 1000℃. More homogeneous microstructure was obtained in all systems by Mn doping due to the α-spinel formation. The varistor performance was drastically improved as non-linear coefficient of α = 22~84. It was found to form Zni (0.20 eV) and V0 (0.33 eV) as dominant defects. The grain boundaries consisted of an electrically single type (0.90~0.93 eV) by the co-doping effect of Mn and Ni. |
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| Key Words |
| ZnO varistor, Mn3O4, NiO, sintering, electrical properties |
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