Modulating Energy Storage Properties in Three-Layered Perovskite Ceramics via Defect Engineering Mechanism

Materials with high phase temperatures are considered among the most promising modern energy storage materials. This is due to their thermal stability, low dielectric loss, and ability to maintain energy density under harsh conditions. In line with these qualities, this research focused on how adding La 3+ , Co 3+ , and Fe 3+ ions to three-layered Aurivillius-phase ceramics affects their dielectric capacitor properties. The co-doped ceramics exhibited a recoverable energy density ( W rec ) of 0.224 J/cm 3 and an energy efficiency ( η ) of 83%. This is a huge improvement compared to the undoped sample, which had a (W rec ) of 0.053 J/cm 3 and an energy efficiency ( η ) of 7%. The enhancement is attributed to the formation of defect dipoles formed by associations between oxygen vacancies and transition metal ions. These defect dipoles generate internal fields that stabilize the polarization and pin domain walls, thereby improving the energy storage performance. Structural analysis reveals that substituting Ti with Co/Fe induces oxygen vacancies and octahedral tilting, thereby significantly diminishing hysteresis. Scanning electron microscopy data demonstrate a reduction in grain size, decreasing from 2.236 to 1.92 μ m. Conversely, temperature-dependent investigations demonstrated a reduction in the Curie temperature ( T c ), specifically from 493 to 387 °C, while maintaining polarization stability up to 300 °C. X-ray photoelectron spectroscopy (XPS) data revealed an increase in the concentration of oxygen vacancies, rising from 11.6% to 23.8%, thus supporting the suggested defect mechanism. These observations imply that Aurivillius ceramics, designed with defects and tri-doped, possess the potential for high-performance dielectric energy storage applications at elevated temperatures.