Electrical properties of SnO₂-ZnO-Nb₂O₅varistor system

Abstract

The electrical properties of (Nb, Zn)-doped SnO2ceramics as an new varistor material were investigated. It was found that there exists a correlation between the nonlinearity of the current density versus the electrical field, the frequency properties of relative permittivity and resistivity. Samples doped with 1.0 mol% ZnO and 0.05 mol% Nb2 O5 , which possess a comparatively low dielectric constant and the highest resistivity of all of the samples investigated, exhibits a higher nonlinear coefficient than the other samples. A defect barrier model for ZnO-based varistor has been adapted to explain the nonlinearity of the SnO2 -based varistor.