Effects of Sn on the microstructure and dielectric properties in BaTiO ₃-based ceramics

Ba_0.985Bi_0.01TiO₃-BaTi _1-xSn_xO₃ powders were synthesized by a two-step soft chemical method. Ceramics with core-shell structure could be easily obtained by using these uniformly distributed powders. The ceramics not only satisfied the requirement of EIA-X8R specification, but also were near to that of EIA-X9R specification. Microstructural evaluation conducted by X-ray diffraction and scanning electron microscopy confirmed the hierarchical structure of the ceramic grains. The shape of the ε-T curves near the dielectric peak became broad when x increased from 0.001 to 0.02. The permittivity of Ba_0.985Bi_0.01TiO₃-BaTi _0.98Sn_0.02O₃ ceramic was ∼23,000, ΔC/C_{20 °C} was -15%, 14.4% and -15% at -55 °C, 120 °C and 170 °C, respectively, and the dielectric loss was 0.5. The results showed that the content of Sn had a strong impact on the diffusion and the dielectric properties of the ceramics.