Physical properties of nanoscale TiO2 with mild rare earth ion doping

Abstract

In this report, we present the spectroscopic features of nanostructured undoped and RE (rare earth) doped TiO₂ system. Undoped an RE doped TiO₂ nanostructures were fabricated using conventional sol-gel method. The structural properties of synthesized nanostructures were characterized by X-ray diffractrogram (XRD) and high resolution transmission electron microscopy (HRTEM). XRD spectra shows the anatase phase of TiO₂ in all the spectra and HRTEM image shows ~ 7nm particle size for the all the samples. The spectroscopic properties were studied by UV-Visible spectroscopy, Fourier transformed infrared spectroscopy and photoluminescence spectroscopy. The emissions due to color centers and oxygen vacancies of TiO₂ were also evident in the PL spectra. The luminescent property of Tb and Eu-doped TiO₂ samples has been studied and it showed selected D-F transition. A weak emission peak at ~490 and ~544 nm corresponding to ⁵D₄→⁷F_6,5 transition of Tb³⁺. Whereas Eu doped TiO₂ nanoparticles exhibited different intra 4f Eu³⁺ ion related transitions with the most intense red emission (⁵D₀→⁷F₂) peak observable at ~613 nm.