Universal Polarization Switching Behavior of Disordered Ferroelectrics

Abstract

Universal scaling features of polarization switching are established experimentally in rather different classes of disordered ferroelectrics: in well-studied lead-zirconate titanate (PZT) ferroelectrics, in recently synthesized Custabilized 0.94(Bi 1/2 Na 1/2 )TiO 3 -0.06BaTiO 3 (BNT-BT) relaxor ferroelectrics, and in classical organic ferroelectrics P(VDF-TrFE). These scaling properties are explained by an extended concept of an inhomogeneous fi eld mechanism (IFM) of polarization dynamics in ferroelectrics. Accordingly, disordered ferroelectrics exhibit a wide spectrum of characteristic switching times due to a statistical distribution of values of the local electric fi eld. How this distribution can be extracted from polarization measurements is demonstrated. Generally, it is shown that the polarization response is primarily controlled by the statistical characteristics of disorder rather than by a temporal law of the local polarization switching.

Polarization dynamics across the morphotropic phase boundary in Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3 ferroelectrics

“…3 To obtain microscopic parameters providing the macroscopic switching process, more sophisticated theories are required, which account for a statistical distribution of local switching times in a system. [4][5][6][7][8] To this end, the inhomogeneous field mechanism (IFM) model is used in this paper, which derives the distribution of times from the distribution of randomly distributed local field values. 7,8 The lead-free (1Àx)Ba(Zr 0.2 Ti 0.8 )O 3 -x(Ba 0.7 Ca 0.3 )TiO 3 ferroelectrics (referred to as BCZT100x hereafter) were chosen for this case study for their prominent properties, which are discussed in the following.…”

“…1 cannot be fitted satisfactorily by the KAI model. Therefore, the recently introduced IFM model 7,8 was utilized to analyze the switching properties of BCZT100x ceramics. This model assumes a statistical distribution of switching times due to a distribution of local field values.…”

Strain Mechanisms in Lead-Free Ferroelectrics for Actuators

“…242 Although, the induced phase transition is of first order, the subsequent switching of the domains formed is a kinetic process that requires time. 73,[441][442][443] Therefore, it is expected that each sub-cycle allows a gradual increase in the amount of switching. The gradual increase of the values after each sub-cycle is analogous to the increase of the values observed with increasing field strength in pulse experiments ( Figure 5.46).…”

“…Therefore, increasing electric field above − leads to saturation. Since switching is a thermally activated kinetic process 73,[441][442][443] , the macroscopic observation of the anomalies ascribed to the development of the ferroelectric long-range order in the small and large signal properties depends on frequency. Since the small signal properties under bias-field were measured with a 0.05 Hz large signal base waveform (Section 4.4.2.2), inherent differences are expected with the large signal results performed at 1 Hz.…”

“…143,144 It is noted that the removal of the electric field leads to a decay of 65 % in the polarization of BNT-0.25ST, indicating that although in BNT-0.25ST is higher than in BNT-0.28ST, it still has considerably lower values than its . Domain switching is a time-dependent kinetic process 73,[441][442][443] , while a first order phase transition is an infinitely fast discontinuous process occurring in the terahertz range. 39,48,444 Therefore, a feasible way to give insight into the nature of the phase transition and the origin of the volume change is to perform polarization and strain measurements at a rate faster than the time domain where the switching processes should occur.…”