NEAR-EDGE AND FINE STRUCTURE OF TITANIUM OXIDES. Se Ahn Song(1), Jae Cheol Lee(1), K.Yu. Pogrebitsky(2) and O.A. Usov(2). 1 Samsung Advanced Institute of Technology, P.O.Box 111, Suwon, 440-600, Korea;

2 Ioffe Phys.-Tech.Institute, Polytechnical str., 26, St. Petersburg, 194021, Russia.

The X-ray absorption spectra (near-edge, fine structure) of TiO₂ and related oxides were measured by total electron yield (TEY) mode at laboratory device, using channeltron. The powder was checked by X-ray diffraction at RT to assure the rutile structure and its unit cell parameters were determined. The average size of crystallites was found by SEM to be within the range of absorption length of material. The effect of particle size for such prepared samples on the TEY amplitude is expected to be negligible. The threshold and minimum XAFSenergy were fitted to provide small oscillations XRD functions at low R-space distances. The energy positions of near-edge peaks defined as negative minima of second derivatives are shown to be in a good agreement with the transmission XAFS spectra for TiO₂^[1] and PbTiO₃^[2]. The possibility of multi-electron excitations in the structure is also discussed. The structure parameters of Ti first coordination sphere were calculated by fitting theoretical FT-XAFS data to experiment alone in the specified R-space region. The values of Ti-O distances and the mean squared displacements were found to be in good agreement with the X-ray diffraction and transmission XAFS data, however some differences being attributed to the surface strain effects.

1. B. Poumellec et al, Phys.Rev.,B35(1987)2284-94.

2. N. Sicron et al, Phys.Rev.,B50(1994)13168-80.