Ba-BASED LAYERED FERROELECTRIC RELAXORS

摘要

SrBi_2Ta_2O_9 (SBT) belongs to the class of Bi-layered perovskites with properties useful for applications in non-volatile ferroelectric memories and high temperature piezoelectric sensors. Introduction of large Ba~(2+) ions into the layered structure shifts ferroelectric phase transition toward lower temperatures with simultaneous broadening over wide temperature range. In addition, a strong frequency dispersion of the dielectric response is induced making pure BaBi_2Ta_2O_9 (BBT) relaxor ferroelectric. In this work, ceramics of solid solutions in the system (1-x)SrBi_2Ta_2O_9-xBaBi_2Ta_2O_9 ((1 -x)SBT-xBBT) were synthesized using conventional mixed oxide method and their microstructural and dielectric characterization was performed in a broad frequency and temperature range. The unusual behavior of the dielectric maximum and relaxor properties with x is observed and attributed to different substitution sites for Ba~(2+) ions in a layered structure.