AVS 54th International Symposium
    Advanced Surface Engineering Tuesday Sessions
       Session SE-TuP

Paper SE-TuP8
Photoinduced Friction Force Variation of Polycrystalline Anatase Thin Films

Tuesday, October 16, 2007, 6:00 pm, Room 4C

Session: Advanced Surface Engineering Poster Session
Presenter: N. Arimitsu, Tokyo Institute of Technology, Japan
Authors: N. Arimitsu, Tokyo Institute of Technology, Japan
A. Nakajima, Tokyo Institute of Technology, Japan
Y. Kameshima, Tokyo Institute of Technology, Japan
K. Okada, Tokyo Institute of Technology, Japan
Correspondent: Click to Email

Titanium dioxide (TiO2) thin film has attracted much attention as a photocatalyst. TiO2 surface exhibits conventional photocatalytic oxidation reactions and photoinduced highly hydrophilic conversion. These reactions result in useful properties such as antibacterial functions, self-cleaning, and antifogging. The photoinduced reaction on TiO2 surface has been well studied by various techniques. According to a friction force microscopy (FFM) study using a Si3N4 cantilever, it was revealed that rutile single crystal produce a unique microdomain structure in the surface with a contrast difference by UV illumination.1 Since the tip of the cantilever is hydrophilic, the image contrast implies the difference in hydrophilicity on the surface. Recently, it is reported that the contrast difference after UV illumination was also obtainable on polycrystalline anatase thin film as in the case of rutile single crystal.2 In the present study, we prepared polycrystalline anatase thin films on Si substrates using sol-gel process and O2 plasma treatment3 and investigated the relationship between photoinduced friction force change and photoinduced hydrophilicity of the film. The photoinduced friction force change was evaluated by FFM with a Si3N4 cantilever. Upon UV illumination, the average friction force decreased gradually with decreasing water contact angle until it reached the lower limit. Then, the friction force began to increase with increasing UV illumination time. Detailed relationship among contact angle change, UV illumination period, and friction force change will be discussed.

1R. Wang et al., Nature 388 (1997) 431.
2K. Katsumata et al., Surf. Sci. 579 (2005) 123.
3N. Arimitsu et al., Surf. Coatings Technol. 201 (2006) 3038.