Extrinsic Properties Hard and Soft Ferroelectrics

The reversibility of the spontaneous polarization in ferroelectrics is attributed to their basic property that permits the switching of spontaneous polarization by the 

An understanding of hardening-softening properties can be achieved through the analysis of the domain wall contribution to the polarization response of ferroelectrics. It should be noted here that this is not the only contribution to the polarization response rather, the intrinsic polarization response as well as surface, boundary, and interface effects may also contribute significantly to the total polarization of a ferroelectric material, especially in thin films. However, the dominant contribution to the dielectric, elastic, and piezoelectric properties in ferroelectric materials is extrinsic, and typically originates from displacement of the domain walls [59]. 

A direct observation of the pinning and bowing of a single ferroelectric domain wall under a weak electric field has been described and analyzed by Yang et al. [61]. By 

It is most likely that local Barkhausen jumps observed in ferroelectrics [62-64] at switching field conditions are the next step of the domain wall motion under an external electric field after bending between pinning centers. 

Several models have been proposed that consider the various interactions of the domain wall with electrostatically ordered defect pinning centers. These can be conditionally dassified into three different scenarios with respect to the charged defects destinations adopted during ordering  

---

Extrinsic Properties Hard and Soft Ferroelectrics 74S depinched/soft... 

---