title: EXAFS and XANES investigation of the ETS-10 microporous titanosilicate.
abstract: In this work, we report state-of-the-art analysis of both Ti K-edge high-resolution XANES and EXAFS data collected on the ETS-10 molecular sieve at the GILDA BM8 beamline of the ESRF facility. The interatomic distances and the angles obtained in our EXAFS study are in fair agreement with the single-crystal XRD data of Wang and Jacobson (Chem. Commun. 1999, 973) and with the recent ab initio periodic study of Damin et al. (J. Phys. Chem. B 2004, 108, 1328) Differently from previous EXAFS work (J. Phys. Chem. 1996, 100, 449), our study supports a model of ETS-10 where the Ti atoms are bonded with two equivalent axial oxygen atoms. This model is also able to reproduce the edge and the post-edge region of the XANES spectrum. Conversely, the weak but well-defined pre-edge peak at 4971.3 eV can be explained only by assuming that a fraction of Ti atoms are in a local geometry similar to that of the pentacoordinated Ti sites in the ETS-4 structure. These Ti atoms in ETS-10 should be the terminal of the -Ti-O-Ti-O-Ti- chains, of which the actual number is strongly increased by the high crystal defectivity (Ti vacancies).
authors.affiliation: Department of Inorganic, Physical and Materials Chemistry and NIS Centre of Excellence, Via P. Giuria 7, I-10125 Torino, Italy. carmelo.prestipino@unito.it
authors.forename: C
authors.initials: C
authors.lastname: Prestipino
authors.forename: P L
authors.initials: PL
authors.lastname: Solari
authors.forename: C
authors.initials: C
authors.lastname: Lamberti