Effect of Annealing on Microstructure and Capacitance Properties of Sol-gel TiO2 Film on Aluminum

Sol-gel TiO2 film prepared by dip-coating on aluminum was annealed under different temperatures, and subsequently anodized in ammonium adipate solution. The microstructure and capacitance properties of TiO2 film on aluminum was investigated by X-ray diffraction (XRD), Raman spectroscopy (RS), thermogravimetric differential scanning calorimetry (TG-DSC), atomic force microscope (AFM), and capacitance temperature (C-T) test, respectively. The results indicated that TiO2 film on aluminum annealed at 400 oC and 500 oC showed nanocrystalline anatase in 1-5nm and 5-12nm particles, respectively, while that annealed at 600 oC showed mixed nanocrystalline phase (anatase and rutile) in 5-15nm particles. The anatase quantity developed remarkably with annealing temperature. The controlling factor of phase transformation of Sol-gel TiO2 film was annealing temperature, and the aluminum foil substrate had little effect. Compared to specimens without TiO2 film, the specific capacitance of TiO2 coated specimens after anodizing at 400 oC, 500 oC and 600 oC was increased by 15%, 35% and 74%, respectively.