FWF - POLDERs - Polarization Decorrelation Regions in Perovskite Relaxors

Relaxor materials are disordered ferroelectrics that recently gained much attention for their high thermally stable dielectric permittivity and high-frequency tunability. Due to their slim polarization hysteresis loop, they also possess very high recoverable energy density. These properties make them attractive as variable capacitors for telecommunications, or as energy storage devices. In this project, the perovskite ferroelectric BaTiO3 will be taken as polar lattice matrix, and both polar and non-polar POLDERSs will be incorporated and controlled by substituting Nb5+ (heterovalent) and Zr4+ (homovalent) simultaneously and with different Nb/Zr ratios respectively at the perovskite B-site. Real-space mapping by molecular dynamics (MD), coupled with experimental neutron scattering pair distribution functions (PDF), will elucidate the relative size of polar and non-polar POLDERS within the parent matrix. MD calculations will then be correlated with the macroscopic dielectric/ferroelectric properties, and the structure of the lattice, both of which will be measured on ceramic samples. This way, the relationship between POLDER size, polarity, distribution and the macroscopic properties will be elucidated.