Synergistic Optimization Unveils Remarkable Energy Storage Enhancement in Silver Niobate-Based Ceramics

AgNbO₃ (AN)-based lead-free antiferroelectric (AFE) ceramic materials have garnered significant research attention due to their distinctive AFE structures and potential applications in pulse dielectric capacitor devices. However, their inferior energy storage performance (ESP) has hindered further advancements in practical use. To address this challenge, we introduce a synergistic optimization strategy aimed at enhancing the ESP of AN-based ceramics. Initially, we incorporate Bi³⁺ ions into the A-site and Ta⁵⁺ ions into the B-site of the ABO₃-structured AN crystal lattice. This deliberate modification leverages the smaller radius of Bi³⁺ ions compared to Ag⁺ ions, effectively reducing the tolerance factor and enhancing oxygen octahedral torsion, thereby stabilizing the AFE phase. Additionally, the hybridization of Bi³⁺ ions’ 6s orbitals with O^2- ions’ 2p orbitals amplifies polarization. By finely adjusting the Nb⁵⁺/Ta⁵⁺ ion concentration ratio to control the AFE and paraelectric phase content, we regulate the electric field-induced polarization and its response trajectory, ultimately improving the ESP of the materials while minimizing hysteresis. Comprehensive characterization of (Ag_0.955Bi_0.015)(Nb_1-xTa_x)O₃ ceramics was performed through X-ray diffraction refinement, temperature-dependent dielectric properties, and transmission electron microscopy, revealing the intricate interplay between atoms, structure, and properties. Our investigation culminates in demonstrating an ultrahigh recoverable energy storage density of 7.06 J/cm³ and an energy storage efficiency of 75% at 470 kV/cm in (Ag_0.955Bi_0.015)(Nb_0.75Ta_0.25)O₃ ceramics, accompanied by exceptional temperature stability from room temperature to 140 °C. This systematic research lays the groundwork for fabricating AN-based ceramic capacitors with enhanced ESP through the synergistic optimization strategy.