Journal of the American Ceramic Society, Vol.102, No.6, 3438-3447, 2019
Energy storage properties in Ba5LaTi3Ta7O30 tungsten bronze ceramics
Ba5LaTi3Ta7O30 tungsten bronze ceramics is a typical linear dielectric with high dielectric constant and low loss, which is expected as a promising candidate for energy-storage application. In the present work, energy-storage properties of Ba5LaTi3Ta7O30 tungsten bronze ceramics were investigated, and the dielectric breakdown mechanism was also discussed based on the morphology of the fracture surface. Dense ceramics were obtained by sintering at temperatures from 1500 to 1575 degrees C. Both the dielectric constant and dielectric strength show strong dependences on the sample density. Optimal dielectric constant of 159, dielectric strength of 639 kV/cm, and energy storage density of 2.9 J/cm(3) were obtained for ceramics sintered at 1550 degrees C, that have the highest density and fine grains. The dielectric strength and energy storage density were also highly dependent on the sample thickness. For ceramics sintered at 1525 degrees C, the dielectric strength increases from 283 to 585 kV/cm while the energy storage density increases from 0.5 to 2.3 J/cm(3) when the thickness changes from 0.5 to 0.2 mm. A thermal breakdown mechanism was adopted to understand the breakdown process in the present ceramics.