Monoclinic domain populations and enhancement of piezoelectric properties in a PZT single crystal at the morphotropic phase boundary

The origin of the strong piezoelectric phenomenon in PbZr1-xTixO3 (PZT) perovskites still suffers from a lack of complete understanding. It concerns the distinction between the intrinsic and extrinsic mechanisms that govern PZT's piezo activity. These two mechanisms have been investigated in single crystal PbZr0.54Ti0.46O3 at the morphotropic phase boundary. After poling in a DC electric field, the piezoelectric properties were examined on the same crystal by observing piezoelectric resonances to determine the piezoelectric coefficient d31 and measuring quasistatic deformation to determine the coefficient d33. The domain populations were investigated during and after poling in a DC electric field. These populations were also investigated as a function of DC fields for strengths similar to those used to measure quasistatic piezoelectric properties for a poled crystal. The experiments indicate that the intrinsic origin of the enhancement of the piezoelectric properties is connected with a change in the population of domains with monoclinic symmetry, in which there is an easy polarization rotation under the action of the electric field.