Drift of charged defects in local fields as a mechanism of degradation in ferroelectrics

Two-dimensional model of point defect migration in ferroelectrics is advanced. Charge defect drift-diffusion in local depolarization fields is considered as a mechanism for aging in ferroelectrics. Numerical results are given for the coupled problems of point defect transport and electrostatic field relaxation in a 2D domain configuration. Peak values of the clamping pressure at domain walls due to space charge formation are in the range of 1divide10 MPa and the consequent coercive field is in the range of 1 kV/mm in agreement with observed coercive stresses and fields in bulk perovskite ferroelectrics.