PbO-deficient PbTiO3: Mass transport, structural effects and possibility for intrinsic screening of the ferroelectric polarization

Intrinsic solid solubility in the form of cation nonstoichiometry has been studied in PbO-deficient bulk PbTiO3 prepared by solid-state reaction. The unit cell distortion, or tetragonality c/a, decreases with increasing concentration of Pb and O vacancies across the solid solubility range. Mass transport during solid-state reaction and sintering is sensitive to the nominal stoichiometry of the system: Excess PbO promotes grain growth and densification while excess TiO2 yields coarsening and swelling. These findings are discussed with respect to thin film growth and screening of the ferroelectric polarization by point defect concentration gradients at epitaxial interfaces.