Dielectric and energy-storage performance of Ba0.5Sr0.5TiO3-SiO2 ceramic-glass composites

Ba0.5Sr0.5TiO3 (BST) nanoparticles coated with SiO2 were used as the starting material to prepare BST-xSiO2 (x = 0, 1.0, 2.0, 3.0, 4.0 and 5.0 wt%) ceramic-glass composites. The coated SiO2 results in the sintered composites with a lower porosity. All the composites exhibited an almost frequency independent dielectric constant that corresponds with a quite low dielectric loss (tanδ < 0.02) over a frequency range from 100 Hz to 1 MHz. It is found that the Curie temperature decreased with increasing x due to the reaction between the SiO2 and BST. As the x increased, the dielectric constant of the composites decreased and the electric breakdown strength increased. Interestingly, it is also found that the charge-discharge efficiency increased with an increasing x. The energy-storage density of more than 2.5 J/cm3 with a charge-discharge efficiency of about 80% was achieved in the composite with x = 1.0 wt%.