Dielectric Properties of Layer Structured Pr3+ - or La3+ - doped SrBiNb2O9 Ceramics

Due to excellent fatigue-resistant properties of SrBi2Nb2O9, SrBi2Ta2O9 and SrBi2 (Nbx, Ta1-x)2O9, it has been considered as one of the most promising candidates for non-volatile random access memories. A lot of research has been conducted to improve the properties of this kind of materials by doping. In this paper, SrBi2-xPrxNb2O9 (x = 0, 0.04 and 0.2) and SrBi1.65La0.35Nb2O9 ferroelectric ceramics with single phase layered Perovskite were prepared by a conventional solid state processing and the effect of La³⁺ - or Pr³⁺ - ions substitution to Bi⁺³ site on dielectric properties of SrBi2Nb2O9 investigated. There is a transition from a normal ferroelectrics to a relaxor ferroelectrics by doping Pr³⁺ or La³⁺ ions into (Bi2O2)²⁺ layers. The substitution of Pr³⁺ ions for Bi³⁺ ions resulted in a decrease from 110 kV/cm for SrBi2-xPrxNb2O9 (x = 0) to 98 kV/cm and 90 kV/cm (x = 0.04 and 0.2) in the coercive field and remanent polarization. It may be helpful to better understand the layered Perovskite relaxation because of the finding of the relaxor behavior in SrBi2-xPrxNb2O9. The dielectric relaxation of SrBi1.65La0.35Nb2O9 obeys Vögel-Fulcher relationship and the activation energy and static freezing temperature obtained are 0.0088 eV and 326.30 K, respectively.