Effect of SiO₂ addition on the dielectric properties and microstructure of BaTiO₃-based ceramics in reducing sintering

The effect of SiO₂ doping on the sintering behavior, microstructure, and dielectric properties of BaTiO₃-based ceramics has been investigated. Silica was added to the BaTiO₃-based powder prepared by the solid state method with 0.075mol%, 0.15mol%, and 0.3mol%, respectively. The SiO₂-doped BaTiO₃-based ceramic with high density and uniform grain size were obtained, which were sintered in reducing atmosphere. A scanning electron microscope, X-ray diffraction, and LCR meter were used to determine the microstructure as well as the dielectric properties. SiO₂ can form a liquid phase belonging to the ternary system of BaO-TiO₂-SiO₂, leading to the formation of BaTiO₃ ceramics with high density at a lower sintering temperature. The SiO₂-doped BaTiO₃-based ceramics can be sintered to a theoretical density higher than 95% at 1220℃ with a soaking time of 2 h. The dielectric constants of the sample with 0.15mol% SiO₂ addition sintered at 1220℃ is about 9000. Doping with a small amount of silica can improve the sintering and dielectric properties of BaTiO₃-based ceramics.