CaTiO₃ linear dielectric ceramics with greatly enhanced dielectric strength and energy storage density

Abstract

CaTiO 3 is a typical linear dielectric material with high dielectric constant, low dielectric loss, and high resistivity, which is expected as a promising candidate for the high energy storage density applications. In the previous work, an energy density of 1.5 J/cm 3 was obtained in CaTiO 3 ceramics, where the dielectric strength was only 435 kV/cm. In fact, the intrinsic dielectric strength of CaTiO 3 is predicted as high as 4.2 MV/cm. Therefore, it should be a challenge issue to enhance the dielectric strength and energy storage density of CaTiO 3 ceramics by optimizing the microstructures. In the present work, dense CaTiO 3 ceramics with fine and uniform microstructures are prepared by spark plasma sintering, and the greatly enhanced dielectric strength (910 kV/cm) and energy storage density (6.9 J/cm 3 ) are obtained. This can be ascribed to the improved resistivity and thermal conductivity, associated with the fine and uniform microstructures. The different post-breakdown features of CaTiO 3 ceramics prepared by different process well interpret why the enhanced dielectric strength is achieved in the SPS sample. The energy storage density can be further improved to 11.8 J/cm 3 by introducing the amorphous alumina thin films as the charge blocking layer, where the dielectric strength is 1188 kV/cm. K E Y W O R D Sdielectric materials/properties, perovskites, spark plasma sintering

Energy storage properties in Ba5LaTi3Ta7O30 tungsten bronze ceramics

“…The intrinsic dielectric strength in many linear dielectrics is much higher than 1 MV/cm, while the dielectric strength of ceramics are usually much lower due to the effects of many extrinsic factors, including the bulk density/porosity, grain size, defect chemistry, and sample size . Recently, enhanced dielectric strength and high‐energy density have been obtained in CaTiO 3 ceramics with fine grains by Zr 4+ modification or advanced sintering method like Spark plasma sintering (SPS) . Generally, ceramics with fine grains have more insulated grain boundaries and less porosity, and exhibit a lower electrical conductivity and a higher thermal conductivity, which promote the improvement of the dielectric strength .…”

“…Recently, enhanced dielectric strength and high‐energy density have been obtained in CaTiO 3 ceramics with fine grains by Zr 4+ modification or advanced sintering method like Spark plasma sintering (SPS) . Generally, ceramics with fine grains have more insulated grain boundaries and less porosity, and exhibit a lower electrical conductivity and a higher thermal conductivity, which promote the improvement of the dielectric strength . Both the calculated and experimental results indicate that the intrinsic dielectric strength can be approached by well controlling the extrinsic factors, thus, high‐energy storage density can be achieved in linear dielectrics.…”

“…So far, research on the energy storage ceramics based on linear dielectrics (or paraelectric materials) is quite limited. Moreover, the existing researches are mainly focused on CaTiO 3 , SrTiO 3 , and TiO 2 ‐based ceramics. It is necessary to explore more linear dielectric systems with good energy storage properties.…”

Improved dielectric strength and energy storage density in Ba6−3xLa8+2xTi18O54 (x = 0.5, 2/3, and 0.75) ceramics

“…Among all types of dielectrics, linear dielectrics possess moderate permittivities independent of electric field, whose energy storage density can be directly calculated by , where ε 0 is the vacuum permittivity (~8.85 × 10 −12 F/m), ε r is the dielectric constant, and E b is the dielectric strength . Compared with ferroelectrics, linear dielectrics possess some advantages in energy storage applications, such as high‐dielectric strength, good temperature stability, low dielectric loss, and thus great energy storage efficiency. According to the computational formula for energy storage density in linear dielectrics, energy storage density U is proportional to dielectric constant ε r and the square of dielectric strength E b , indicating that energy storage density can be strongly influenced by dielectric strength, which depends on both intrinsic factors and extrinsic factors.…”

“…The researches on energy storage characteristics in linear dielectrics have been mainly focused on TiO 2 and CaTiO 3 ‐based dielectrics, while relevant studies on ceramics with tungsten bronze structures are rare. Ba 6−3 x La 8+2 x Ti 18 O 54 (0.07 < x < 0.77) is a kind of linear dielectrics at room temperature.…”