Effect of sinter temperature on the electrical properties of TiO2-based capacitor–varistors

Abstract The effect of sinter temperature on the electrical properties of a new TiO 2 -based varistor system, TiO 2 ·Y 2 O 3 ·Nb 2 O 5 , was investigated by measuring the properties of I – V , permittivity and grain-boundary barriers. The varistor of 99.30%TiO 2 ·0.60%Y 2 O 3 ·0.10%Nb 2 O 5 composite sintered at 1400 °C has a maximal nonlinear coefficient of α =7.8, a low reference electrical field of 12.8 V·mm −1 at 1 mA cm −2 , a high density of 4.20 g/cm 3 and the ultrahigh permittivity of more than 85 000 (measured at 1 kHz), which is consistent with its highest and narrowest grain-boundary barriers. Due to these properties the (Nb, Y)-doped TiO 2 varistors sintered at 1400 °C has varistor-capacitance multifunctional components, which are quite useful in the situation that the voltage protection and high-frequency noise absorption are meanwhile required. In order to illustrate the grain-boundary barrier formation in TiO 2 ·Y 2 O 3 ·Nb 2 O 5 varistors, a grain-boundary defect barrier model was also introduced.