Synthesis and characterization of titanium dioxide thin films using scanning electron microscopy, X-ray diffraction and surface reflection FT-IR

We report here the synthesis and characterization of TiO2 thin films using scanning electron microscopy (SEM), X-ray diffraction measurements (XRD) and transmission and surface reflection Fourier transform infrared (FT-IR) measurements. The TiO2 thin films were prepared from a TiO 2 aqueous suspension on polyethylene and sapphire substrates. SEM measurements show that the TiO2 thin films prepared on a sapphire substrate consisted of small particles of about 100 to 1000 nm, isolated pores of about 300 to 500 nm, and large particle aggregates of up to 5000 nm. XRD measurements of the thin films prepared on the sapphire substrate conserved the crystallographic composition of the precursor Degussa P-25 used for the preparation of the films. The principal orientations observed were (101) for anatase and (110) for ruble. Bulk phonons in TiO2 polycrystalline powders (Degussa P-25) were determined from transmission FT-IR measurements at 646 and 503 cm--1. The TiO2 films on the polyethylene substrate have surface phonon modes at 723 and 446 and an unresolved band at about 810 and 830 cm--1. These modes are assigned to surface phonon modes. Surface reflection FT-IR measurements revealed a new band near 842 cm--1 for the TiO2 thin films prepared on a sapphire substrate. This band was attributed to a surface phonon mode characteristic of the large particle aggregates.