Fig. 4

Internal electric field. Internal electric field as a function of the ratio of capacitances for a Pb(Zr,Ti)O₃ (PZT) and b poly(vinylidenefluoride–trifluoroethylene) [P(VDF–TrFE)]. The solid circles represent the initial electric field, directly after the applied voltage drops to zero and the induced polarization is discharged. The open circles represent the retained values of the field after depolarization. The dashed lines represent the corresponding coercive field. When the initial internal field is much lower than the coercive field, there is no depolarization and the initial and final internal fields are identical. When the initial internal field is much larger than the coercive field, the ferroelectric material depolarizes until the final internal field is stabilized at the coercive field, regardless of the ratio C_ferro/C_ser