The dielectric properties and the relaxation phase transition of copper substituted SrBi₂ Nb₂ O₉ ferroelectric ceramics

The dielectric properties and the relaxation phase transition of Sr_1-xCu_xBi₂Nb₂O₉ (SCBN) ferroelectric ceramics prepared by a solid-state process, with x ranging from 0.0 to 0.6, are reported. The microstructure of SrBi₂Nb₂O₉ (SBN) was clearly influenced by Cu²⁺ substituting the Sr²⁺ of SBN, as observed by X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). An obvious enhancement in dielectric constant was observed and the frequency stability was enhanced for copper substituted SBN compared to SBN. At the same time, the sintering temperature of SBN was reduced significantly by approximately 80 ^{{ring operator}}C because of the copper ions being introduced. The maximum dielectric constant peak broadened gradually with increasing copper content, indicating that the phase transition from a normal ferroelectric to a relaxor ferroelectric occurs in SBN.