Effect of Nd{sub}2O{sub}3 and Sm{sub}2O{sub}3 on the Microstructure and Electrical Properties of WO{sub}3 Capacitor-varistor Ceramics

摘要

The effect of Nd{sub}2O{sub}3 and Sm{sub}2O{sub}3 on the microstructure, nonlinear electrical properties, and dielectric properties of WO{sub}3-based ceramics was investigated. The dopant Nd{sub}2O{sub}3 and Sm{sub}2O{sub}3 can promote the grain growth of WO{sub}3 grains. It was also found that Nd{sub}2O{sub}3 and Sm{sub}2O{sub}3 can reduce the breakdown voltages values of WO{sub}3-based ceramics effectively, but do not strongly influence the nonlinear values. The nonlinear coefficient of doped samples was 2-3 and the barrier voltage was very low with the value of 0.04-0.08V. Through impedance analysis, it can be found that those rare earth ions have a great influence on the dielectric properties. The dielectric constant of doped samples was higher than that of undoped samples, and the high dielectric constant makes them suitable as capacitor-varistor materials. The theory of defects in the crystal lattice was introduced to explain the nonlinear electrical behavior of the WO{sub}3-based varistor ceramics.