Effects of silica coating on the microstructures and energy storage properties of BaTiO 3 ceramics

Abstract We investigated microstructures and energy storage properties of SiO 2 -coated BaTiO 3 ceramics that were prepared by the so-called Stober process. The thickness of coating layer of BaTiO 3 powders could be effectively controlled by the silica content. It could be observed that the secondary phases Ba 2 TiSi 2 O 8 appeared in the coated BaTiO 3 ceramics due to the interdiffusion reactions between SiO 2 and BaTiO 3 components under sintering. BaTiO 3 cores in the coated ceramics remained up to the original grain size indicating the coating layer as an inhibitor. The results showed that both breakdown strength and energy density were improved apparently. The homogeneity of silica coating in the ceramics should dominate contribution to breakdown strength, which can reduce the weak-point breakdown under high electric field. The optimized composition for BaTiO 3 ceramic coated with 2.0 wt% SiO 2 showed the maximum energy storage density of 1.2 J/cm 3 with energy storage efficiency of 53.8%, which is about three times higher than that of pure BaTiO 3 (0.37 J/cm 3 ).