Thermodynamics of polydomain ferroelectric bilayers and graded multilayers

The equilibrium domain structure and its evolution under an electric field in ferroelectric bilayers and graded multilayers are considered. The equilibrium bilayer is self-poled and contains single-domain and polydomain (with 180 degrees domains) layers. The polarization of a graded multilayer proceeds by movement of wedge-like domains as a result of progressive transformation of polydomain layers to a single-domain state. The theory provides the principal explanation of dielectric behavior of graded ferroelectric films. (c) 2006 American Institute of Physics.