Enhancing Energy-Storage Characteristics of BNT-based Ceramic via Quadruple Perovskite (AA′3B4O12) Modification

Abstract

Lead-free dielectric ceramics are of interest for pulsed power devices, but achieving high recoverable energy at low/moderate electric fields is still challenging. In this work, (1−x) Bi0.47Na0.47Ba0.06TiO3-xCaCu3Ti4O12 [(1−x) BNBT-xCCTO, x = 0, 0.02, 0.04, 0.06, and 0.08] solid solutions were synthesised by a solid-state route, and their structural and electrical responses were examined. Increasing CCTO modifies the rhombohedral/tetragonal (R-T) phase balance and refines the grain structure. It also promotes polar nanoregions, indicating the development of relaxor behavior. These modifications also raise the activation energy for conduction and appear to suppress interfacial polarisation, which likely contributes to higher breakdown strength. The 0.94BNBT-0.06CCTO composition shows the most promising energy-storage response, delivering Wrec/E ≈ 0.02322 mC cm-2 at a relatively low field (~202 kV cm-1), with Wrec of 4.69 J cm-3 and an efficiency of ~90.47%. This level of performance is competitive with, and in several cases exceeds, recently reported lead-free bulk dielectrics operating in similar field ranges. In addition, the optimised ceramic maintains stable energy storage characteristics up to ~135 °C, over typical low-frequency ranges (~120 Hz), and under repeated cycling (~8×103 cycles). Overall, these results suggest that modest CCTO incorporation is an effective strategy for improving energy storage behaviour in BNBT-based ceramics.