Effect of Ca2+/Hf4+ modification at A/B sites on energy-storage density of Bi0.47Na0.47Ba0.06TiO3 ceramics

• By incorporating CaHfO 3 , the E b is greatly enhanced from 120 kV/cm for BNBT to 280 kV/cm for BNBT-12CH. • BNBT-12CH ceramic achieves a large recoverable energy-storage density of 4.2 J/cm 3 . • The η and W rec of BNBT-12CH ceramic gradually improve with increasing temperature from 25 °C to 140 °C. Pb-free relaxor ferroelectric materials are attractive because of their fast charge–discharge capability and environmental safety. Here, a series of new-type Pb-free ferroelectric ceramics are designed and fabricated: (1 - x )Bi 0.47 Na 0.47 Ba 0.06 TiO 3 - x CaHfO 3 (abbreviated as BNBT- 100x CH). Through the modification of Ca 2+ /Hf 4+ at A/B sites, a wider optical band gap and submicron grains are obtained, and the polar nano regions are induced in the structure. Therefore, an optimal W rec of 4.2 J/cm 3 is obtained for the BNBT-12CH ceramic under 280 kV/cm. In addition, the BNBT-12CH ceramic displays better energy-storage characteristics at high temperatures within the test range of 25–140 °C. All of these features indicate that the modification of BNT-based ceramics by Ca 2+ /Hf 4+ has a significant effect on energy-storage density. This work also offers a novel guidance for the development and application of Hf element.