Spark Plasma Sintering Of BST/Al₂O₃ Ceramics With High Energy Storage Density

As the key materials for energy storage capacitor,ceramic dielectrics possess high dielectric constant,long life,high mechanical strength,and can be used in board temperature ranges.However,the energy storage density of ceramic dielectrics is relatively low because of their low dielectric breakdown strength.In order to improve the energy storage density of Ba_1-xSr_xTiO₃ ceramics,Ba_1-xSr_xTiO₃/Al₂O₃ ceramics were prepared by spark plasma sintering,and their electrical properties and microstructure were systematically investigated.By using spark plasma sintering,the optimal sintering temperature of Ba_1-xSr_xTiO₃ ceramics decreased from?1400? to?1000?.All the spark plasma sintered samples exhibited uniform dense microstructure with fine grains.The dielectric constant and Curie Temperature of Ba_1-xSr_xTiO₃?x = 0.5.0.6.0.7?decreased as the content of Sr2+ increased.It was found that the energy storage density of Ba_1-xSr_xTiO₃ ceramics prepared by spark plasma sintering was much higher than that of the BST ceramics prepared by traditional solid phase sintering.Ba_0.3Sr_0.7TiO₃ ceramics showed the highest energy storage density of 1.47 J/cm3.Ba_0.4Sr_0.6TiO₃/Al₂O₃ composite ceramics were prepared by spark plasma sintering.All the composited ceramics possessed uniform and dense microstructure,and the secondary phase of Al₂O₃ was found to distributed homogeneously in the BST matrix.Addition of Al₂O₃ slightly decreased the dielectric constant and the dielectric loss.The electrical breakdown strength and the maximum energy storage density of Ba_0.4Sr_0.6TiO₃ ceramics were greatly improved by the addition of Al₂O₃.When 1wt%Al₂O₃ was added,the electrical breakdown strength increased from 210 kV/cm to 300 kV/cm and the maximum energy storage density increased from 1.20 J/cm3 to 1.69 J/cm3 respectively.