DEFORMATION-INDUCED FERROELECTRIC DOMAIN PINNING IN CHROMIUM-DOPED LINBO3

We report on the correlation between the dopant-distribution and the location of ferroelectric domains in Czochralski grown, chromium-doped LiNbO3 single crystals. Optical microscopy, scanning electron microscopy and X-ray topography have been used to show that the domain walls follow the steepest gradient of the Cr-concentration. The experimental findings are explained by model calculations assuming that the development of domains is determined by the elastic deformations due to varying dopant concentration within the crystal. The property relating spatially varying deformation to an electrical field within the crystal (which defines the domain polarity) is assumed to be the piezoelectricity of LiNbO3 below the Curie temperature.