Polarization reversal in LiNbO3 crystals under asymmetric diffusion conditions

It is shown that domain inversion in LiNbO3 crystals stimulated by heat treatment depends on boundary conditions. Limitation of outdiffusion from −C surface leads to the appearance of an inverted layer with the thickness more than one-half of a crystal thickness. Consequent indiffusion preserves the bidomain structure but reduces the inverted layer depth. The phenomenon is explained in terms of the built-in electric field caused by diffusion process.