Effect of Dy2O3 and La2O3 on the microstructure and electrical properties of WO3 ceramics

Dy2O3 and La2O3-doped WO3 ceramics were fabricated by conventional ceramic technique and the microstructure, phase structure and electrical properties were studied. There are some porous slice-shaped materials in Dy-doped samples and club-shaped materials in La-doped samples. It is believed that slice-shaped materials (Dy-rich phase) are amorphism with weak conductivity to form the Schottky barrier. However, club-shaped materials (La-rich phase) are crystalline state with good conductivity so that the barrier is broken down, leading the nearly linear current–voltage characteristics. The grain boundary barrier layer capacitor (GBBLC) model cannot account for the high dielectric constant of La-doped sample because of the good conductivity of grain boundary materials. The high dielectric constant is assumed to arise from the high dielectric polarization of La-rich phase in the grain boundary.