Improved energy storage density of Sr0.7Bi0.2TiO3-based relaxor ferroelectric ceramics via a core-shell-structural optimization strategy

Environmentally friendly lead-free dielectric ceramics have attracted much attention due to their high power density, rapid discharge rate and excellent dielectric stability. In this study, the joint strategy of composition design and morphology design is proposed to improve the energy storage performance of Sr0.7Bi0.2TiO3@Ba0.7Ca0.3TiO3 (SBT@BCT) composite ceramics. The SBT@BCT composite ceramics were prepared by coating BCT on the surface of SBT powders in sol–gel process. The results show that an appropriate BCT content can result in the coexistence of the tetragonal and orthogonal nanodomains, reduce the sintering temperature, and reasonably control the grain scale, thus improving the effective polarization, breakdown strength and temperature stability. When BCT coating is 15 mol