Correlation between enhanced lattice polarizability and high piezoelectric response in BiScO3-PbTiO3.

Piezoelectric and ex situ electric-field induced structural studies were carried out on closely spaced compositions in the morphotropic phase boundary region of (1--x) PbTiO3-(x)BiScO3. While the common approach of zero field structural analysis failed to provide a unique relationship between the anomalous piezoresponse of x = 0.3725 and structural factor(s), ex situ study of electric-field induced structural changes revealed that the composition exhibiting the highest piezoelectric response is the one which also exhibits significantly enhanced polarizability of the lattices of both coexisting (monoclinic and tetragonal) phases. The enhanced lattice polarizability manifests as a significant fraction of the monoclinic phase transforming irreversibly to the tetragonal phase after electric poling. [ABSTRACT FROM AUTHOR]