Preparation and Improvement in the Electrical Properties of Lead-zinc-niobate–based Ceramics by Thermal Treatments

The piezoelectric and dielectric properties of Pb(Zn1/3Nb2/3)O3 (PZN)-based ceramics were investigated. The perovskite structure of PZN ceramics was stabilized by the addition of Pb(Zn0.47Ti0.53)O3 (PZT). The highest piezoelectric properties were observed for the composition of 0.5PZN–0.5PZT, which lies on the two-phase zone of morphotropic phase boundary. For further improvements in electric properties, the specimens were thermally treated in a flowing O2 atmosphere at temperatures ranging from 860 to 1030 °C. The thermal treatment eliminated the PbO-rich amorphous intergranular layer by lead evaporation. As a result of this improvement in structure, the dielectric constant (ε′), the piezoelectric coefficient (d33), and the electromechanical coupling factor (kp), were enhanced markedly after thermal annealing at 960 °C for 8 h in an O2 atmosphere.