The Preparation And Properties Of Ba₄Sr₆TiO₃-Based Ceramics With High Energy Storage Density

As the fast development of pulsed power technology and energy storage devices, the demand of environmental electric energy devices with high storage density and high efficiency are gradually increasing. Ceramic-based capacitors have received more and more attention due to their advantages of high dielectric constant and power density, fast responding, long life, good mechanical strength and temperature stability, while the disadvantages of owing much pores, impurities and defects may lead to relatively low dielectric breakdown strength.In order to improve the energy storage density of ceramic dielectrics, spark plasma sintering was used to prepare dense samples with excellent energy storage property which is an advanced approach by the heat of pulsed current and mechanical pressurization at low temperature within several minutes, and SPS has been widely used in all kinds of new materials. Thus this study focuses on Bao.6Sro.4Ti03-based ceramics with two kinds of additives which were sintered by SPS to achieve the purpose of enhancing breakdown strength and energy storage density. The structure, micromorphology, dielectric and energy storage properties were analysed as well, and the results are as following:By using SPS technology, the optimal sintering temperature was decreased almost 300-400℃, and the density of the samlpes were more than 99.9%. Compared with ceramics prepared by conventional solid state sintering, the samples all presents uniform dense microstructure with fine grains, and have dispersed phase transition peak. As a result, ceramics obtained by SPS received better energy storage performance, the breakdown strength and energy storage density are 230kV/cm and 1.28J/cm3 for pure Ba0.6Sr0.4TiO3 ceramics.With the addition of 57%Si02-17%Al203-15%B203-9%ZnO-2%K20 glass powders to Bao.6Sro.4Ti03 ceramics, the breakdown strength was significantly increased from two aspects:(1) As sintering aids, glass can reduce the sintering temperature furtherly; (2) Utilizing the liquid sintering to get uniform and compact microstructure. So it was found that Bao.6Sro.4Ti03-Glass ceramics had a small residual polarization and high dielectric breakdown strength, which led to the significant improvement of energy storage density and efficiency. When the content of glass was 5 wt% in the study, the breakdown strength and energy storage density reached to 440kV/cm and 2.00J/cm3.Added with proper amounts of ZnO in Ba0.6Sr0.4TiO3 ceramics, the dielectric constant remained high values, and the breakdown strength got higher that was benefit from the effect of regulating grain growth. It showed that the energy storage density was improved to 1.55J/cm3, while the breakdown strength is 260kV/cm and the efficiency was as high as 90.1% because of the small residual polarization.