Polarization Decorrelation Regions in Perovskite Relaxors


Relaxor behaviour occurs in chemically-substituted ferroelectrics due to the disruption of the long-range correlation of cation displacements. Substitution can be performed either with homovalent or heterovalent cations. Then either non-polar regions are created in the polar lattice matrix, or polar defect complexes are formed, respectively. These non-polar or polar Polarization Decorrelation Regions (POLDERs) have different correlation length and can respond differently to the applied electric fields. In heterovalent-substituted (non chargecompensated) Ba-based perovskites, relaxor behaviour appears for much lower substituent contents than in homovalent-substituted ones (e.g. at 7 wt.% substituent content against 35 wt.%, respectively). It is vital to study the formation, distribution and interaction of polar and nonpolar POLDERs on the nano- to mesoscale in order to tune macroscopic dielectric properties in these relaxors. This project for the first time will study the role of POLDERs in disrupting longrange ferroelectricity.