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

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)Bi0.47Na0.47Ba0.06TiO3-xCaHfO3 (abbreviated as BNBT-100xCH). Through the modification of Ca2+/Hf4+ 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 Wrec of 4.2 J/cm3 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 Ca2+/Hf4+ has a significant effect on energy-storage density. This work also offers a novel guidance for the development and application of Hf element.