(Ba0.5Sr0.5)TiO3 modification on etched aluminum foil for electrolytic capacitor

A new method was proposed to form (Ba_0.5Sr_0.5)TiO₃–Al₂O₃ composite oxide film on etched aluminum foils. The specimens were covered with (Ba_0.5Sr_0.5)TiO₃ (BST) layer by dip-coating in citrate solution and subsequent heat-treatment under 400–650 °C, finally by anodizing in a hot boracic acid and borate solution. The BST powders heated under different temperatures were characterized by X-ray diffraction (XRD) and the specific capacitance of the coated specimens heat-treated under different temperatures and times was measured. It is found that the specific capacitance increases initially with enhancing the temperature and reaches to maximum at 550 °C, but slightly decreases with the heat-treatment time. The capacitance was increased by about 35% after BST coating.