TiO2/Ca9Al(PO4)7 composites with enhanced dielectric breakdown strength and energy storage density

Linear dielectric ceramics have attracted extensive attention in dielectric capacitors because of their high dielectric breakdown strength (DBS), low loss and wide working temperature. In this work, some TiO2/Ca9Al(PO4)(7) composites were prepared through conventional solid-state reaction using rutile TiO2 powder and CaO-P2O5-Al2O3-SiO2 (CPSA) glass powder at the weight ratio of (100 - x) wt% TiO2-x wt% CPSA (0 <= x <= 50). The microstructure analysis shows that the addition of CPSA glass powder is helpful in obtaining uniform fine grain ceramics and reducing the porosity. The complex impedance spectrum elucidates that the activation energy of grain and grain boundary increased with the increase of Ca9Al(PO4)(7) (CAP) content. The sample with x = 40 exhibits a high DBS of 99.2 kV/mm and an energy storage density of 1.88 J/cm(3), which are more than 2.3 times that of the sample with x = 0. It provides an effective way to enhance the DBS and energy storage density of TiO2 based ceramics.