Controlling the crystallinity of Aurivillius Bi₄Ti₃O₁₂ films for energy storage applications

The film microstructure, ferroelectric properties, breakdown strength and energy-storage performance of lead-free Aurivillius-phase Bi₄Ti₃O₁₂ (BiTO) films were systematically investigated by adjusting the oxygen pressure during pulsed laser deposition. X-ray diffraction patterns indicate that all BiTO films exhibited c -axis orientation. Notably, the BiTO film deposited at a moderate oxygen pressure of 0.08 mbar achieved the highest recoverable energy-storage density of 143.6 J/cm³, along with an excellent energy efficiency of 90.1 %. These results are attributed to a slim polarization loop, high maximum polarization, and a relatively high breakdown strength. In addition, the optimized BiTO film demonstrated an outstanding thermal stability up to 200 °C and superior fatigue endurance of up to 10¹⁰ cycles. These achievements provide an effective strategy for developing dielectric capacitors for high-performance energy-storage devices operating at elevated temperatures.