Características elétricas do sistema varistor ZnO.Bi2O3.Co2O 3.MnO2 dopado com Ni2O3

The effect of nickel oxide addition on the electrical properties of the ZnO. Bi2O3. Co2O3. MnO2 varistor system was investigated. This system was sintered at 1100 oC, 1150 oC, 1200 oC and 1250 oC for one hour and electrical measurements (current density as a function of the applied electrical field) were carried out. The microstructural analyses were performed by scanning electron microscopy and X-ray diffraction. The best electrical properties were obtained for the system containing 1.0 mol% of nickel oxide, and sintered at 1100 oC. A degradation in the electrical properties with increasing sintering temperature has been observed, probably due to an increase in the microstructural heterogeneity.