Investigation of electrical properties of SnO2•Co2O3•Sb2O3 varistor system

The effect of Sb2O3 on the electrical and physical properties of SnO2-based ceramics were investigated by measuring the densities, permittivities, the properties of V-I and boundary barriers. SnO2 (.) Co2O3 ceramics cannot exhibit electrical nonlinearity. A little amount of Sb2O3 can improve the nonlinear properties of the samples greatly. The height and width of the defect barriers were calculated. It was found that the sample doped with 0.01 mol% Sb2O3 exhibits the highest density (rho = 6.90 g/cm(3)), the highest reference electrical field and the best electrical nonlinearity (alpha = 12.9), which is consistent to its highest and narrowest defect barriers. The effect of Sb2O3 dopants can be explained by the substitution and segregation of antimony ions. The effect of cooling rate was also investigated. The samples cooled at 2 degreesC/min exhibit better nonlinear electrical properties. A grain-boundary defect barrier model Of SnO2 (.) Co2O3 (.) Sb2O3 varistor was also introduced. (C) 2001 Elsevier Science B.V. All rights reserved.