Effects of fatigue and damage on the hysteresis loops of ferroelectric ceramics

Abstract

Electric fatigue and radiation damage may induce pinched polarization hysteresis loops and asymmetric strain hysteresis loops of ferroelectric ceramics, respectively. Based on a gradual domain switching model, this paper formulates a novel constitutive model to investigate the hysteresis deformation behavior of ferroelectric ceramics by radiation damage and electric fatigue. First, two important physical mechanisms, namely, alignment of the defect dipoles and domain-wall pinning due to diffusion of charged defects, are considered in irradiated ferroelectric ceramics. It is found that the alignment of the defect dipoles acts as an internal field and increases the coercive field, while the domain-wall pinning clamps the domain and causes the vanishment of remanent polarization. Second, the effects of point defects and domain pinning by space charges are taken into account in ferroelectric fatigue model. The results of simulations reveal that the spatial distribution and electric property of space charges play a dominant role in the asymmetry of strain hysteresis loops. The proposed model can elucidate experimental phenomena reported in the literature.