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.
Polarization Decorrelation Regions in Perovskite Relaxors