Effects of Bi ³⁺ content and grain size on electrical properties of SrBi ₂Ta ₂O ₉ ceramic

SrBi ₂Ta ₂O ₉ ceramics with various excess Bi ₂O ₃ content were synthesized by conventional solid state method. The effects of excess Bi ³⁺ content on structure and electrical properties were investigated. XRD analysis indicated that a typical bismuth layer polycrystalline structure was gained. Plate-like grains with different size were observed by SEM. With the occurrence of a liquid phase during sintering process, the excess Bi ₂O ₃ content greatly influenced densification and grain size of as-prepared ceramics, which determine microstructure and electrical properties of these samples to some extent. The results also found that the electrical properties were consistent with grain size. The sample with 5% excess Bi ₂O ₃ could exhibit a better hysteresis loop, with relative density and dielectric constant of about 96.8% and 149, respectively.