Studies On Preparation, Characterization And Properties Of Nano TiO₂ And TiO₂/SiO₂ Composite Thin Film

Nano titanium dioxide is of favorable biological and chemical inertness, strong oxidizability, low cost and long-term stability against photocorrosion and chemical corrosion. Nano TiO₂ and TiO₂/SiO₂ thin films are used photocatalysis degradation materials and self-cleaing materials, and can kill bacteria and virus.At present it is the hot spot in the research of photocatalysis, and it is of great value in the practical applications.Firstly, butyl titanate was used as precursor and the uniform and transparent nano titanium dioxide thin films were prepared successfully by Sol-Gel method in this paper. According to the experimental results, the optimum ratio of the materials was shown. The thin films of excellent adhesive power can be obtained by the appropriate substrate's pretreatment, 1.70-2.20 Sol viscosity and 2mm/s coating velocity.Then properties of nano TiO₂ thin films were studied. The results showed that there was a linear relationship between the TiO₂ thin film thickness and the number of coating cycles, but the line didn't go through the origin. Particle diameter increased gradually with increasing thin film thickness. The phase of thin films changed absolutely to anatase from amorphous phase at 550℃, and at last changed to rutile by heat treatment about 850℃. The average grain size increased gradually with increasing heat treatment temperature.Secondly, nano TiO₂/SiO₂ composite thin films were prepared by two-step hydrolyze method. The results indicated that the phase structure changed from amorphous phase to anatase, then to rutile, but the changed temperature enhanced. Grain size increased gradually with increasing temperature. SiO₂ content caused transformation of particle size and the percent of phase. With the increasing content of SiO₂, grain size decreased and crystalline phase had the trend of translating to low-temperature phase. According to the infrared spectrometric analyzer, when sample didn't undergo heat treatment many organic group occur in the nano thin film. On the condition of upper temperature the organic group were eliminate little by little, and characteristic absorption peak of TiO₂ is obvious.Finally, hydrophilicity and photocatalytic activity of nano thin films were researched. The thickness of thin films affected unobviousdly hydrophilicity and photocatalytic activity increased gradually along with increasing thickness of films.