Charge and polarization distributions at the 90° domain wall in barium titanate ferroelectric

Ferroelectric FE materials exhibit domains over which the atom displacements lead to a net dipole polarization in one direction alternating with domains with the polarization in another direction. In the tetragonal phase the polarization changes by 180° or 90°. These domains can be switched by applying external electric fields or stresses, leading to broad applications in transducers, actuators, capacitors, and memories. The nature of the domain boundary and the mechanism by which the domains switch determine the performance properties. In addition they are probably important in determining the mechanical and electrical failures associated with aging. In order to understand the origin of these phenomena and to design materials with improved performance, particularly as devices are miniaturized into the nanoscale, it would be most useful to have a detailed understanding of the structural and dynamic properties of the domain boundaries. There are some data from both experiment and theory on the 180° domain boundary; however, much less is known about the 90° domain walls observed in the perovskite tetragonal phase.