X-RAY-INVESTIGATIONS OF THE SURFACE-LAYERS OF THE PEROVSKITE-TYPE FERROELECTRIC-CRYSTALS

The physical nature of surface layers of the BaTiO3 and PbTiO3 ferroel ectric perovskite-type crystals has been investigated by X-ray diffrac tion. It has been found that the surface layers with an extremely high piezoelectric deformation are formed at the positive electrode at roo m temperature under the influence of the de electric field. This effec t is caused by a nonlinear potential distribution. The thickness and t he piezoelectric deformation of the surface layer increase with the ex ternal electric field. The time of formation of the negative space cha rge layer in the anodic region is close to the Maxwell relaxation time . The Schottky-type surface potential barrier, existing in the absence of the external electric field, is formed as a result of capture of t he electric charge carriers by the surface states.