Effects of Bi3+ content and grain size on electrical properties of SrBi2Ta2O9 ceramic

SrBi2Ta2O9 ceramics with various excess Bi2O3 content were synthesized by conventional solid state method. The effects of excess Bi3+ 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 Bi2O3 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 Bi2O3 could exhibit a better hysteresis loop, with relative density and dielectric constant of about 96.8% and 149, respectively.

► SrBi2Ta2O9 pellets with various excess Bi2O3 were obtained by solid state method.
► Electrical properties are affected by the amount of excess Bi2O3 and grain size.
► Sample with x=5% shows much better microstructure and higher electrical properties.