Abstract
The energy storage density of ferroelectric capacitors is mainly determined by their polarization and breakdown strength. In this work, the energy storage performance of BNT thin films was enhanced by introducing an amorphous alumina to construct Al2O3-Bi0.5Na0.5TiO3 (AO-BNT) heterojunctions by sol-gel process. The results reveal that the Bi0.5Na0.5TiO3/Al2O3/Bi0.5Na0.5TiO3 (BNT/AO/BNT) structure significantly improves the breakdown strength of BNT, the breakdown electric field is increased from 1050 to 3082 kV/cm, and the energy storage density is also increased from 8.7 to 19.9 J/cm3. This is mainly due to the built-in electric field formed by the opposite double-heterojunction can counteract part of the external electric field, and this capacitor-like structure concentrated more applied electric field on the amorphous alumina with better breakdown ability, thus provides a new way to improve the energy storage performance of dielectric ferroelectric capacitors.