Investigation of electrical properties of SnO 2·Co 2O 3·Sb 2O 3 varistor system

Abstract

The effect of Sb 2O 3 on the electrical and physical properties of SnO 2-based ceramics were investigated by measuring the densities, permittivities, the properties of V– I and boundary barriers. SnO 2·Co 2O 3 ceramics cannot exhibit electrical nonlinearity. A little amount of Sb 2O 3 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% Sb 2O 3 exhibits the highest density ( ρ=6.90 g/cm 3), the highest reference electrical field and the best electrical nonlinearity ( α=12.9), which is consistent to its highest and narrowest defect barriers. The effect of Sb 2O 3 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°C/min exhibit better nonlinear electrical properties. A grain-boundary defect barrier model of SnO 2·Co 2O 3·Sb 2O 3 varistor was also introduced.