Phase field simulation of de-aging process in acceptor-doped ferroelectrics

A phenomenological de-aging model with uniformly distributed defect dipoles for acceptor-doped ferroelectrics is proposed with the dynamic switching process of defect dipoles being simulated by the kinetic Monte Carlo method. The shifted P-E loops at different frequencies and temperatures were theoretically investigated. The results showed that the internal bias field increases with frequency and decreases with temperature. The scaling relation of the internal bias field with frequency was calculated at 298 K, 318 K and 338 K. The number of defect dipoles along different directions was calculated during the de-aging process, which is a key factor affecting the shape of P-E hysteresis loop. At 0.1 Hz, the defect dipoles can align with the polarization direction, but when the frequency is more than 10 Hz, they could not follow the field change and the internal bias field will saturate to a fixed value as the field frequency is beyond 100 Hz.