| 초록 |
Titanium dioxide (TiO2) thin films have been widely investigated in photocatalysis application fields such as hydrophilicity, self-cleaning, optical coatings, and purification of air and toxic gases because of their excellent chemical stability, photocatalytic decomposition of organics and contaminants, mechanical hardness, optical transmittance with high refractive index, and strong redox ability. In this study, in order to develop a hydrophilicity mirror, TiO2 films are deposited on the Cr and amorphous-TiO2 substrate. The crystal structures were analyzed by XRD and FE-SEM and AFM. The contact angle measurements of water were performed at room temperature using a commercial contact angle meter. In TiO2/Cr, a mixed phase comprising of anatase and rutile is formed. In TiO2/amorphous-TiO2/Cr, pure anatase phase is obtained. The amorphous-TiO2 film as interlayer tends to induce micro-columnar shaped anatase phase. The formation of anatase phase leads to an abrupt decrease of the contact angle by UV-irradiation. Hydrophilic to hydrophobic reconversion by electron-hole recombination is retarded, which seems to be due to pure anatase phase without rutile phase. It is desirable that the contact angle rises slowly in a dark place, and maintains low value for a long time, because in practical applications, UV light cannot always be irradiated. In this study, over-layer coating of SiO2 was performed to maintain low the contact angle. Consequently, SiO2/TiO2/TiO2/Cr multilayer thin film showed the contact angle of less than 20o for 36h-storage time in the dark. |
