Nonlinear electrical behaviour of the TiO2 center dot Y2O3 center dot Nb2O5 system

The nonlinear and dielectric properties of a new TiO2-based varistor system , TiO2.Y2O3. Nb2O5, have been investigated. The (Nb, Y)-doped TiO2 ceramics have nonlinear coefficients of alpha = 5 - 8 and a lower breakdown electri cal field of 6-12 V mm(-1), in which the varistor of (99.3mol%)TiO2 (0.6mol %)Y2O3 (0.1 mol%)Nb2O5 composite sintered at 1400 degrees C has a nonlinear coefficient of alpha = 7.8 and a maximum breakdown electrical field of 12 V.mm(-1) at 1 mA.cm(-2). Also, the relative dielectric constants of the com posite reach more than 85 000, which is almost unchanged within the tempera ture range from -20 to 280 degrees C and the frequency range of 0.5 K-2 MHz . Due to these properties the (Nb, Y)-doped TiO2 varistor has varistor-capa citance bifunctional components, which are quite useful in the situation th at the voltage protection and high-frequency noise absorption are meanwhile required.