Coercive field dependence of the grain size of ferroelectric films

The coercive field (E_c) of Pb(Zr_0.55Ti_0.45)O₃ film was experimentally observed showing a paraboliclike relationship with grain size d. The curvature of E_c−d increased as the film thickness decreased. A phenomenological theory was developed to describe the experimental results, taking into account the contributions of domain wall motion and domain structure transition to the polarization switching. The simulated results agreed with the experimental results very well. In addition to the paraboliclike E_c−d curve, it was also found that the influence of thickness on the curvature was attributed to the dielectric dependence on the film thickness.