Enhanced energy storage density of antiferroelectric AgNbO3-based ceramics by Bi/Ta modification at A/B sites

Dielectric capacitors have attracted extensive attention due to their high power density along with fast charge/discharge rate. Despite the high energy storage performance were obtained in lead-based ceramics, we still need to find lead-free ceramic alternatives considering the environmental requirements, and AgNbO3 has received extensive attention owing to its ferroelectric–antiferroelectric (FE–AFE) phase transition. In our study, the AFE properties of the samples were improved by tuning the grain size and polarizability of ions, and excellent energy storage performance was obtained in Bi/Ta co-doped AgNbO3. The BANT ceramic exhibited a remarkably enhanced recoverable energy density of 3.9 J/cm3 and acceptable efficiency of 61%. Morphological and structural analyses and electrical properties revealed that this co-substitution can optimize the AFE properties of the material, which can be demonstrated by the slim P–E loops and the reduced grain sizes. Of note, the BANT6 ceramic exhibited fast discharge speed accompanied by the actual energy storage density of up to 3.5 J/cm3 under 260 kV/cm. These findings indicate that AgNbO3-based AFE ceramics are a prospective alternative for energy storage materials applied to high-pulse-power fields.