Effects of Kaolinite addition on the densification and dielectric properties of BaTiO3 ceramics

Commercial Kaolinite was employed as sintering aid to reduce the sintering temperature of BaTiO3 ceramics. The effects of Kaolinite content and sintering temperature on the densification, microstructure and dielectric properties of BaTiO3 ceramics have been investigated. The density characterization results show that the addition of Kaolinite significantly lowered the sintering temperature of BaTiO3 ceramics to about 1200 °C. XRD results show BaTiO3 ceramics with a low amount of Kaolinite exhibited perovskite structure, but 10.0 wt% Kaolinite additions resulted in the formation of a secondary phase, BaAl2Si2O8. BaO–TiO2–Al2O3–SiO2 glass phase was formed and improved the average breakdown strength of ceramics, which was supported by SEM-EDX results. The Kaolinite content had shown a strong influence on the dielectric constant and the diffuse transition. BaTiO3 ceramic with 4.0 wt% Kaolinite addition possessed well temperature stability of dielectric constant.

► Commercial Kaolinite was employed as sintering aid for BaTiO3 ceramics.
► BaO–TiO2–Al2O3–SiO2 glass was formed due to the reaction between BaTiO3 and Kaolinite.
► The addition of Kaolinite greatly improved the breakdown strength of BaTiO3 ceramics.
► BaTiO3 ceramic with Kaolinite addition exhibited a diffuse phase transition.