Eu (III) as a probe in titania thin films: The effect of temperature

Titania oxide films doped with europium were prepared by the sol–gel process and deposited on glass substrates by the dip-coating technique. The fluorescence and excitation spectra of the Eu (III) in the films changed as the calcination temperature rose. TiO2:Eu thin films were heat-treated at various temperatures (100, 200, 300, 400 and 500 °C), resulting in transparent films. Excitation spectra presented a change in the charge transfer band (CTB) with increasing temperature. Eu (III) emission spectra exhibited transitions arising mainly from the 5D0 level to the 7FJ (J = 0–4) manifolds. The lifetime of the 5D0 → 7F2 transition of the Eu (III) ion increased in the samples heated-treated up to 400 °C, while the lifetime of the sample treated at 500 °C decreased, probably due to a change in the crystalline structure of the TiO2.