Effects of Oxygen Vacancy on Ferroelectric Hysteresis under External Electric and Stress Fields

Effects of oxygen vacancies on properties of ferroelectric materials were investigated through their hysteresis characteristics using Monte Carlo simulation. The purpose of this work is to study the roles of oxygen vacancy in ferroelectrics. The 2D four-state Potts model was considered for dipole switching. Under the application of external electric and stress fields, for both static and periodic field conditions, the electrical polarization and strain were numerically calculated with varying stress field and oxygen-vacancy probability (or concentration). It was found that, with or without an applied stress, the coercivity, remnant and saturation of the ferroelectric and elastic properties decrease with increasing oxygen vacancies. Moreover, under an applied periodic stress, the shapes of strain-electric-field butterfly loops were found similar to those obtained from applying the combination of two static stresses.