A CHARACTERIZATION OF TITANIUM ANODIC OXIDES BY X-RAY-ABSORPTION SPECTROSCOPY AND GRAZING X-RAY-DIFFRACTION

Thin oxide layers obtained by electrochemical oxidation of titanium we re studied using grazing X-ray diffraction (GXRD) and X-ray absorption spectroscopy (XAS). In the precursor state the layers, with thickness es ranging from 15 to 105 nm, appeared to be amorphous by GXRD whereas a short-range order is detected via XAS with a first O shell and a se cond Ti shell, rather similar to those of crystallized anatase. Subseq uent treatments of the layers such as aging under polarization or ther mal annealing led to ordering on a larger scale and to crystallization in the anatase form.