Characterization of structure and luminescence of titania nanotubes

Abstract

The morphology, structural, and optical properties of porous titania layers prepared by electrochemical oxidation of Ti foils are studied as a function of technological conditions of preparation and post-electrochemical-oxidation thermal treatment. Ti foils were anodized in aqueous and non-aqueous HF and H3PO4 solutions by applying various anodizing conditions. Titania nanotubes with diameters ranging from 30 nm to 250 nm with controlled length have been prepared. The influence of thermal treatment upon the structural properties of TiO2 nanotubes was investigated by means of X-ray diffraction analysis and Raman scattering. It was found that the as prepared samples are amorphous. As the annealing temperature increases to 300ｰC, an anatase structure is formed. Starting from 500ｰC, a rutile structure is produced which coexists with the anatase structure. A complete phase transition to the rutile structure occurs at 800ｰC. The luminescence from both anatase and rutile phases was observed at low temperatures. The origin of luminescence bands is discussed.