Ti K-edge XANES studies of Ti coordination and disorder in oxide compounds: Comparison between theory and experiment
- Laboratoire de Physique et Mecanique des Geomateriaux, Universite de Marne-la-vallee (and UA CNRS 734 and LURE), 93166 Noisy le Grand cedex (France)
- Department of Geological and Environmental Sciences and Stanford Synchrotron Radiation Laboratory, Stanford University, Stanford, California 94305-2115 (United States)
- Department of Physics, University of Washington, Seattle, Washington 98195 (United States)
Experimental Ti K-edge x-ray-absorption near-edge structure (XANES) spectra for a variety of Ti(IV)-bearing crystalline oxide model compounds are compared with those calculated using the {ital ab initio} multiple-scattering code FEFF7. A scattering-theoretic interpretation of various features in the experimental spectra, including pre-edge and main-edge peaks, is presented together with an interpretation of the effects of disorder. The observed pre-edge features are found to vary in both position (by {approx}2{plus_minus}0.1eV) and normalized height (from {approx}0.04 to 1.0{plus_minus}0.05) as a function of Ti coordination (4, 5, or 6 oxygen nearest neighbors), in agreement with calculations. In aperiodic oxide compounds where the Ti coordination is unknown (e.g., titanosilicate glasses and melts), pre-edge position and height can be used to derive reliable information on Ti coordination chemistry. For example, one can distinguish between fivefold coordinated Ti (i.e., TiO{sub 5}) and a 50:50 mixture of fourfold- and sixfold-coordinated Ti (i.e., TiO{sub 4} vs TiO{sub 6}). Finally, it is proposed that the intensity of the main-edge features can be used as a probe of disorder in the short- and medium-range environment of Ti. This is exemplified by Ti XANES studies of the effect of radiation damage on CaTiSiO{sub 5} and the melting of K{sub 2}TiSi{sub 2}O{sub 7} glass at high temperature. {copyright} {ital 1997} {ital The American Physical Society}
- DOE Contract Number:
- FG06-90ER45415
- OSTI ID:
- 656108
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 56, Issue 4; Other Information: PBD: Jul 1997
- Country of Publication:
- United States
- Language:
- English
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