Abstract
The composition dependence of dielectric and piezoelectric nonlinearities were characterized in epitaxially grown (0.3)Pb(Ni0.33Nb0.67)O3-(0.7)Pb(ZrxTi1−x)O3 thin films deposited on SrTiO3. Tetragonal, morphotropic phase boundary (MPB) and rhombohedral films were prepared by changing the Zr/Ti ratio. The relative dielectric permittivity ɛr and the converse piezoelectric coefficient d33,f were found to follow the Rayleigh law. The local piezoelectric nonlinearity map showed the formation of micron-sized clusters of higher nonlinear activity for the MPB and rhombohedral compositions. The ratios of the irreversible to the reversible Rayleigh constants αɛ/ɛinit and the spatially averaged αd/d33,init ratio were larger for the rhombohedral and MPB compositions compared to the tetragonal composition. The larger dielectric and piezoelectric nonlinearities observed for the rhombohedral sample are interpreted in terms of a higher domain wall mobility due to a smaller ferroelectric distortion and superior crystal quality.
