Anomalously High Lateral Polarization in Spherulitic Thin Films of Lead Zirconate Titanate

The factors that may cause the effect (found experimentally previously) of a strong change in the lateral projection of polarization (calculated based on second optical harmonic measurements) in thin polycrystalline spherulitic films of lead zirconate titanate with a change in the geometric sizes of perovskite blocks in the range from 10–15 to 35–40 µm have been considered. It is suggested that these changes are caused by the action of strong lateral stresses, leading to a change in the film microstructure, reorientation of the ferroelectric polarization in the directions maximally close to the substrate plane, and formation of induced polarization. The maximally possible contributions of these stresses to the observed effect, when the film composition is close to the morphotropic phase boundary from the side of the rhombohedral modification of the ferroelectric phase, are estimated.