Preparation and Properties of TiO2-SiO2 Multifunctional Thin Films

To improve the antifogging property of normal glasses, uniform and transparent xTiO2-(1−x)SiO2 (x=1.00, 0.75, 0.50, 0.25, 0) composite thin films were prepared on glass substrates by sol-gel dip-coating method and subsequent calcination at 500 ℃ for one hour. The microstructure of TiO2-SiO2 was characterized by X-ray diffraction (XRD). The surface morphology and roughness of the films were tested with a field emission scanning electron microscope (SEM) and an atom force microscope (AFM). The optical property and wettability of TiO2-SiO2 thin films were measured with a ultraviolet-visible spectrophometer and a contact angle tester, respectively. The antifogging properties of glass with and without TiO2-SiO2 thin films were evaluated by hot water bath experiment. The XRD results showed that the crystalline phase of TiO2-SiO2 was composed by anatase TiO2 and amorphous SiO2. The phase structure of TiO2-SiO2 changed with SiO2 content. With the SiO2 content increased, the diffraction peak of TiO2-SiO2 became wider and weaker, which indicated that the degree of crystallization was weakened. There was only one broad diffraction peak around 25° while the SiO2 content was higher than 75%. This showed that 0.25TiO2-0.75SiO2 and SiO2 was amorphous phase. SEM and AFM results indicated that the surface of TiO2-SiO2 thin films with SiO2 less than 50% was uniform and dense, while the roughness of the films was small. When the content of SiO2 was higher than 75%, some large particles appeared on the surface of the composite films, which increased the surface roughness. The optical properties of TiO2-SiO2 thin films were also affected by the SiO2 content. When the content of SiO2 was higher than 50%, the average transmittance of TiO2-SiO2 films was higher than 85% in the visible wavelength range. The average transmittance of SiO2 film was up to 91.36% in visible wavelength range, which was higher than that of uncoated glass. The average transmittance of TiO2-SiO2 film was increased with the increase of SiO2 content, which might be due to the low refractive index of SiO2. The surface wettability of the films was related to the microstructure, chemical composition, surface roughness and surface hydroxyl content. All the deposited films were hydrophilic in the experiment. When the SiO2 content was less than 50%, the water contact angles of TiO2-SiO2 film were smaller than 5°. And the films were characterized as superhydrophilic. Based on the hot water bath experiment, 0.75TiO2-0.25SiO2, 0.50TiO2-0.50SiO2 and 0.25TiO2-0.75SiO2 thin films showed excellent antifogging property. The good antifogging property might benefit from the superhydrophilic of the film, which could make the small water drops spread and form water films. Among them, 0.50TiO2-0.50SiO2 contained anatase phase TiO2 and amorphous SiO2, which had good photocatalytic activity. It also had high transparent in visible wavelength range and excellent antifogging property. Therefore, the 0.50TiO2-0.50SiO2 thin film could act as a multifunctional film for glass surface modification. The durability of the 0.50TiO2-0.50SiO2 film was evaluated by exposing the film in ambient environment for 60 days. The results showed that the average transmittance of the 0.50TiO2-0.50SiO2 composite film remained above 84%. It also had good antifogging property. These results show that the 0.50TiO2-0.50SiO2 composite thin film prepared on glass surface has high transparency, good antifogging property and durability, which has many potential application prospects, including solar cell, eyeglasses, display devices and other filed. © 2023 Chongqing Wujiu Periodicals Press. All rights reserved.