A theory of polarization reversals in ferroelectrics near the morphotropicphase boundary of perovskite-type oxides

A theory of polarization reversals near the morphotropic phase boundary in perovskite-type oxides was developed on the basis of the Landau-Khalatnikov equation of motion. It was found that for a weak electric field, the polar ization reversal takes place through a rotation of polarization, and it bec omes faster upon approaching the morphotropic phase boundary. It was clarif ied that a saddle point in the free energy as a function of polarization pl ays an important role in this type of polarization reversal.