Impact of Structure Ordering and Defects on Properties of Complex Ferroelectric Perovskites

Influence of the structure ordering, modification and defects on the properties in ferroelectric ceramics and thin films are investigated. Structural changes in perovskite type compounds with general formula (1-x)Pb(B3+ ,Nb)TiO3 -xPbTiO(3) are realized by variation of it composition (by exchange of ions B3+ in B sublattice). The crystallographic features of Pb(Lu1/2Nb1/2)O-3-PbTiO3 (PLuNT) and PbSc1/2 Nb1/2O3-PbLu1/2Nb1/2O3 (PSN-PLuN) compounds are discussed with respect to dielectric, polarization and electro-mechanical properties. The heterovalent substitution of Pb2+ by La3+ in PLuNT ceramics either in both components and maintaining the PbTiO3 unmodified shifts the MPB to the pseudomonoclinic side of phase diagram. The initial unmodified material "softens"--coercive field E c decreases and simultaneously high values of maximum and remnant polarization are characteristic. Antiferroelectric thin films display higher radiation resistance than ferroelectric heterostructures up to a neutron fluence of 2*10(22) m(-2) (E > 0.1 MeV). The strong dependence of radiation-induced change of properties from the quality of the films (epitaxial versus polycrystalline) was found.