PREPARATION OF FUNCTIONAL TIO2 FILMS BY PULSED LASER DEPOSITION ON PROPER SUBSTRATES
Authors: Sin-iti Kitazawa, Nuclear Science Research Institute, Japan Atomic Energy Agency (JAEA), Tokai, Naka, Ibaraki, Japan
Abstract: The optical properties of titanium dioxide (TiO2), the most promising material for photocatalysis, vary in accordance with its band structure, crystalline structure, size effect and so on. In the case of a pure titanium dioxide thin solid film, the parameters which determine photocatalytic activity are easily identifiable. The band structures reveal the character of the crystalline structure, with rutile and anatase being the most common form. The size effect is relevant when the size of the crystals is small enough to create a quantum size effect. In short, the activity of photocatalysis in a pure titanium dioxide thin film depends upon the character of rutile and anatase in the structure. The optical properties also vary, depending on the size of the crystal grains and their orientation even within the same crystal structure. Furthermore, a properly balanced mixture of rutile and anatase may provide good optical properties by drawing upon the advantages of each structure. Pulsed laser deposition (PLD) is suitable as a way to prepare titanium dioxide thin films. With PLD, it is possible to prepare thin films according to the desired composition ratio and crystal structure in a manner that controls for sputtered titanium and oxygen atoms. In this chapter, we describe the effect of a proper substrate with respect to the crystal structure of prepared titanium dioxide thin films using PLD. In addition, the preparation procedure, surface morphology and methods for evaluating the prepared films are shown in the course of the narrative.