Liquid Phase Deposition Preparation Of Tio <sub> 2 </ Sub> Thin Films

Many kinds of technologies of preparation of functional thin film are on the bright way of development with the extensive application of oxide thin film in more and more fields. In rough, the preparation methods can be divided into physical method, such as the method of evaporation, the method of sputtering, and chemical method, such as the method of CVD, the method of sol-gel and the method of electrodeposit. Using chemical method in preparation of film, little energy needed and little influence on environment made. Chemical method is common reception and is called soft-process as the attention of the world is being drawn by the problem of environment and energy sources today.In recent years, one method called Liquid Phase Deposition (LPD) was developed among wet chemical methods. In 1988, Nagayama firstly reported this method. After immersing substrate in certain solution, uniform and compact thin film of oxide or hydroxide will be obtained on substrate. During the formation of thin film, heat treatment and expensive equipment are not required. Furthermore, the operation of the formation of film is simple.Because of research being deficient in the preparation of thin film by LPD, no systemic reports on the preparation of TiO2 thin film by LPD and the tremendous potential of LPD in industrialization and commercialization, study of preparation of Ti02 film was carried on.In this paper, the non-crystal Ti02 film or anatase nano-crystalline film would be obtained on glass substrate after the substrate was immersed in aqueousadded H3BO3. In the first time, systemic discussion on effect of [TiFe]2- concentration, [TiFe]2-/ H3BO3 molar ratio, deposition time and heat treatment on the surface structure and performance of deposited thin films made. The photocatalytic activity of thin film and deposit powder, and hydrophilicity of thin film were investigated. The transparence, thickness, and crystal structure of the deposited films were characterized by XRD, SEM and UV-Vis absorption spectroscopy. The results of research showed the following:(1)Transparent Ti02 film could be obtained in certain concentration of (NH4)2TiF6, which was in the range of 0.05~0.2mol/l in aqueous (NH4)2TiF6. If the concentrationof (NH4)2TiF6 was below 0.01mol/1, thin film could not be obtained.(2)Transparent TiO2 film could be obtained when H3BO3/ [TiF6]2-molar ratio was kept at 2 ~ 6/1.(3)The reaction temperature should be controlled at 15~90C, then Transparent TiO2 film could be obtained. When the reaction temperature was bellowed 10C, no film was obtained.(4) The increase of thickness of thin film was brought by polymerization of [TiF6-n(OH)n]2-. And the face of crystalline of thin film had certain direction because of the direction of polymerization of [TiF6-n(OH)n]2- on glass substrate.(5)The prepared TiO2 thin film showed some features of hydrophilicity and photocatalytic activity whether the thin film came through heat treatment or not.