A novel double-coating approach to prepare fine-grained BaTiO3@La2O3@SiO2 dielectric ceramics for energy storage application

Abstract We prepared submicron BaTiO 3 @La 2 O 3 @SiO 2 particles with high uniformity and dispersity using a novel double-coating method. The monodispersed submicron BaTiO 3 particles (diameter about 240 nm) formed a ferroelectric core that was coated with La 2 O 3 and SiO 2 as a modified layer and a layer with high electrical resistance, respectively, and the thickness of two shells was about 20 nm. We then obtained dense, fine-grained BaTiO 3 -based energy storage ceramics (grain size ≤ 300 nm) with the same particle structure by means of sintering in air at 1240 °C for 2 h. As the amount of SiO 2 increased, the content of the tetragonal phase and the densification first increased and then decreased. When the amount of SiO 2 exceeded 9.0 wt%, a secondary phase with Ba 2 TiSi 2 O 8 appeared, and the core-shell structure disappeared. The BaTiO 3 @La 2 O 3 @SiO 2 ceramics met the X8R requirements, with a maximum dielectric constant of 3362 at 6.0 wt% SiO 2 , and a low dielectric loss at room temperature ( 2 , while the energy storage density first increased and then decreased as the amount of SiO 2 coating increased from 0.0 to 12.0 wt%. The discharged energy storage density was highest (0.54 J/cm 3 ) for samples containing 9.0 wt% SiO 2 under a maximum polarization field of 13.6 kV/mm, and the energy storage efficiency of the ceramic was >85%.