Effects of electric fatigue on the butterfly curves of ferroelectric ceramics

The major obstacle for further expansion of the applications of ferroelectric materials is the limited durability and reliability. Recent experiments demonstrated that after a certain number of electric loading cycles, a ferroelectric ceramic may exhibit different strain hysteresis loops on its different positions. Based on a gradual domain switching model, the present paper formulates the strain loops of ferroelectric ceramics induced by electric fatigue. The mechanisms of point defects and domain pinning by space charges are considered in the fatigue model. Our simulations reveal that the spatial distribution and electric property of space charges play a dominant role in the asymmetry of strain loops, while the evolution law of domain switching influences the smoothness of curves. It is found that with the increase in electric loading cycles, both the longitudinal and the transverse strain loops become asymmetric.