AVS 53rd International Symposium
    Nano-Manufacturing Topical Conference Tuesday Sessions
       Session NM-TuP

Paper NM-TuP2
Annealing Effect of Structural, Morphological and Optical Properties on Reactive Sputtered WO@sub3@ Films for Mediated Heterogeneous Photocatalyst

Tuesday, November 14, 2006, 6:00 pm, Room 3rd Floor Lobby

Session: Nano-Manufacturing Poster Session
Presenter: K. Takahashi, University of Toyama, Japan
Authors: K. Prabakar, University of Toyama, Japan
T. Takahashi, University of Toyama, Japan
K. Takahashi, University of Toyama, Japan
T. Nezuka, University of Toyama, Japan
T. Nakashima, Kashiwa Chuo High School, Japan
Y. Kubota, University of Yokohama City, Japan
A. Fujishima, Kanagawa Academy of Science and Technology, Japan
Correspondent: Click to Email
The WO@sub3@ mediated heterogeneous photocatalyst for the oxidation of pollutants in air would be useful study for environmental decontamination purposes. Reactive facing target sputtering method was used to deposit WO@sub3@ thin films from a metal tungsten disc in an Ar+O@sub2@ mixture gas atmosphere at different sputtering pressures. X-Ray diffraction, scanning electron microscopy, UV-vis spectrophotometer in the wavelength range 300 to 900 nm and Raman spectroscopy studies were performed to study structural, surface morphology and the optical properties of the as-deposited and annealed samples. Annealing treatments were done in oxygen atmospheres. All the as-deposited films were amorphous in structure. The films annealed at 400°C and deposited at 100 W have monoclinic crystal structure with the preferential orientation of (111) plane. As the sputtering power increases to 200 W and annealed at 400°C, a changes in the crystalline orientation of the films along the (001) direction is observed. SEM images show a denser granular structure with grains having different shapes and sizes. The WO@sub3@ films deposited at the sputtering pressure of 0.15 Pa and annealed at 400°C show the nanorods like growth from the observation of SEM images. The optical absorption edge of the as-deposited films prepared at the sputtering pressures of 0.8 - 0.15 Pa varied between 340 - 380 nm and shifted up to 470 nm when the samples are annealed at 400 °C. From the measurement of Raman spectra, it was observed that the O - W@super6+@ - O bonds, and the W@super6+@=O stretching mode of terminal atoms on the surface of WO@sub3@ microcrystalline grains. The suitability of the films for the WO@sub3@/TiO@sub2@ heterogeneous photocatalyst were analyzed and discussed.