Growth behavior and microstructure of arc ion plated titanium dioxide

The experimental results show that the calculated free energy for rutile phase growth is lower than for anatase, and that the rutile phase grows preferentially if thermodynamically satisfactory oxygen supply (in terms of oxygen partial pressure) is present, although less activation energy is required for anatase growth. However, OES studies reveal that, with further increased oxygen partial pressure and extended deposition time, oxidation occurring at the cathode surface generates a higher amount of neutral titanium atoms and, consequently, the metastable anatase phase grows. Detailed TEM microstructural characterization of the deposited TiO2 films in this study also explicitly shows that films identified as XRD amorphous actually contain very fine rutile nanocrystallites within the amorphous structure, whereas films revealed by XRD as composed predominantly of the anatase phase are actually as a consequence of later growth, preceded by rutile growth in the initial stage.