Effect of SiO2 additive on dielectric response and energy storage performance of Ba0.4Sr0.6TiO3 ceramics

SiO2-added barium strontium titanate ceramics Ba0.4Sr0.6TiO3-xwt%SiO2 (x=0, 0.5, 1, 3, BSTSx) were prepared via a traditional solid state reaction method. The effect of SiO2 additive on the microstructure, dielectric response and energy storage properties was investigated. The results confirmed that with the increase of SiO2 additive, diffuse phase transition arises and the dielectric constant decreases. An equivalent circuit model and Arrhenius law were used to calculate the activation energy of grain and grain boundary, which indicated that the dielectric relaxation at high temperature was caused by oxygen vacancy. While appropriate SiO2 additive led to improve the breakdown strength, further increase of SiO2 deteriorated the energy storage because of the low densification. Finally, optimized energy storage performance was obtained for BSTS0.5 ceramics: dielectric constant of 1002, dielectric loss of 0.45%, energy density of 0.86 J/cm3 and energy storage efficiency of 79% at 134 kV/cm.