From core-shell particles to dense Ba0.8Sr0.2Zr0.1Ti0.9O3@Bi2O3-Fe2O3-SiO2 ceramics with low sintering temperature and improved dielectric, energy storage properties

To achieve high energy storage in dielectric ceramics, a new designed material Ba0.8Sr0.2Zr0.1Ti0.9O3@Bi2O3-Fe2O3-SiO2 with core-shell structure was fabricated by the monodispersed submicron Ba0.8Sr0.2Zr0.1Ti0.9O3 particles (diameter similar to 180 nm) coated with the 25-nm-thick shell of Bi2O3-Fe2O3-SiO2. The influences of Bi2O3-Fe2O3-SiO2 amount, Bi/Fe ratio, and sintering temperature on the phase composition, microstructure, and ceramic electrical properties were investigated. X-ray diffraction analysis of the ceramics revealed the formation of perovskite Ba0.8Sr0.2Zr0.1Ti0.9O3 when the Bi2O3-Fe2O3-SiO2 amount was below 6.0 wt%. The secondary phases Bi2Fe4O9 and Bi4Ti3O12 formed in ceramics when the Bi2O3-Fe2O3-SiO2 amount exceeded 6.0 wt%, as the ceramic grain core-shell structure collapsed. Based on FESEM images, the densification of ceramics can be tenderly controlled at low sintering temperature, and the ceramic grains can maintain their core-shell structure. As the Bi2O3-Fe2O3-SiO2 amount, the ratio of Bi to Fe, and the sintering temperature increase, the ceramic room temperature dielectric constant increases up to a maximum value then decreases. The energy storage density exhibits a similar tendency to increase first and then decrease. Fine-grained Ba0.8Sr0.2Zr0.1Ti0.9O3@Bi2O3-Fe2O3-SiO2 ceramics with Bi/Fe ratio of 1.04 and 6.0 wt% Bi2O3-Fe2O3-SiO2 sintered at 1120 degrees C had a dielectric constant of 2599, the maximum energy storage density of 1.50 J/cm(3) under 29.31 kV/mm. This work proposed a novel method to enhance electrical properties of functional materials, which could be potentially used in the fabrication of capacitors with high energy storage performance.