Understanding the thermal evolution of TiO2 mesoporous thin films using XANES at Ti L-edge and O K-edge

L. ANDRINI; P. C. ANGELOMÉ; G. J. A. A. SOLER ILLIA; B.S. MUN; F. G. REQUEJO

Foz do Iguaçu

Conferencia; International Conference on Electronic Spectroscopy and Structure; 2006

We have investigated the electronic structure of TiO2 mesoporous films prepared by XXX and supported on different substrates like Si, FTO and ITO and treated at different temperatures between room temperature and 500 °C in air, through X-ray absorption spectroscopy at O K-edges and Ti L-edges (TEY mode) at beamline 9.3.2 at the ALS. By Ti L-XANES spectra we can determine the local order of Ti-atoms, which can be clearly distinguished between Ti in amorphous-like TiO2 with lower average coordination number than six and TiO2 in crystalline state as six-folded Ti in anatase-TiO2. Oxygen K-edge follows this crystallization by broadening of the peak feature. We can conclude that this crystallization process occurs between 300 – 500 °C and strongly depends on the type of substrate, being highly ordered at lower temperature in the following trend: S > ITO > FTO.