Effect of ZnO and CuO on the sintering temperature and piezoelectric properties of a hard piezoelectric ceramic

Hard piezoelectrics with high dielectric and piezoelectric constants are used for high-power applications. However, the sintering temperature of these ceramics is high, around 1200 degrees C, restricting the usage of cheap base metal electrodes in fabrication of multi-layer components. This study investigates the effect of CuO and ZnO on the sintering temperature of a hard piezoelectric, APC 841, which is a MnO2- and Nb2O5-modified PZT. The addition of CuO decreased the sintering temperature through the formation of a liquid phase. However, the piezoelectric properties of the CuO-added ceramics sintered at <= 950 degrees C were lower than the desired values. The addition of ZnO resulted in a significant improvement in the piezoelectric properties. This enhancement was attributed to the formation of a homogeneous microstructure with large grains. The APC 841 + 0.2 wt% CuO + 1.1 wt% ZnO ceramics sintered at 950 degrees C showed excellent piezoelectric and dielectric properties with values of k(p) = 0.532, Q(m) = 750, d(33) = 351 pC/N, epsilon(33)/epsilon(0) = 1337, and T-c = 280 degrees C.