Preparation and electrical properties of an anodized Al₂O ₃-BaTiO₃ composite film

A highly stable, water-based barium titanate BaTiO₃, BT, sol was synthesized using a sol-gel route through a chelate lactate technique. Dried BT precursor powders were measured by thermal gravimetry-differential thermal analysis and X-ray diffraction. It was found that BT powders first converted into barium carbonate BaCO₃, Ti complex, and intermediate phase Ba₂Ti₂O₅CO₃, and then transformed into perovskite phase BaTiO₃. The crystallization temperature was about 550°C. The low-voltage etched aluminum foils were covered with BT sol by dip coating, and then annealed at 600°C for 30 min in air. After that, the samples were anodized in a 15 wt% aqueous solution of ammonium adipate. The voltage-time variations during anodizing were monitored, and the electrical properties of the anodic oxide film were examined. It was shown that the specific capacitance, the product of specific capacitance and withstanding voltage, and leakage current of samples with a BT coating were about 48.93%, 38.50%, and 167% larger than that without a BT coating, respectively.