TiO2 thin films were prepared by using a reactive DC magnetron sputtering method with Ar ion-beam assistance. The effect of the Ar ion-beam current on the structural and optical properties of the reactive magnetron sputtered TiO2 thin films was studied. The as-deposited films were subjected to annealing with the atmospheric environment, and the change of film properties after annealing was investigated. When the Ar ion-beam assistance was applied, the deposited TiO2 thin films were found to induce a higher deposition rate, a higher packing density and refractive index, a lower extinction coefficient, and a smoother surface than that of the film deposited without ion-beam assistance. The structures of all as-deposited films were amorphous. In the annealing process, the ion-beam-assisted TiO2 thin films had a phase transition from amorphous to anatase polycrystalline with a strong TiO2 anatase (101) peak at a temperature of 400 degreesC. At above 400 degreesC, the refractive index of deposited films increased by an anatase structure and the extinction coefficient increased due to a reduction in the oxidation of TiO2 thin films. (C) 2004 Elsevier B.V. All rights reserved.