Synchrotron Radiation Ti‐k XANES Study of TiO₂─Y₂O₃‐Stabilized Tetragonal Zirconia Polycrystals

Abstract

Valence state and site symmetry of Ti ions in Ti0,-Y,O,-ZrO, powders with 2 mol% Y,O, and 5, 10, 15, and 20 mol% TiO,, respectively, are studied by X-ray absorption near-edge spectroscopy (XANES). Tetravalent Z P ions are replaced predominantly by Ti4+ ions. Within the solubility region of Ti ions, a subsequent displacement of Ti ions from the center of symmetry is observed with increasing TiO, content in Ti0,-Y,O,-stabilized tetragonal ZrO, polycrystals (Ti-Y-TZP) under investigation. This behavior cannot be interpreted with a random substitution of Ti4+ ions on Zr4+ lattice sites. On the contrary, this correlation between the TiO, content in Ti-Y-TZP and the shift of Ti ions indicates an increasing interaction between the Ti ionswith growing TiO, content, caused by a subsequent clustering of Ti ions.

EXAFS and XANES studies of silica-titania sol-gel films

“…The value for Ti-K XANES spectra of different gels and glassy films. Ba2TiO4 is too low compared to the literature data, 0.43 [10], probably due to some problem during the experimental preparation of this standard. This prepeak corresponds to a Is-3d transition which is only allowed when the polyhedron around Ti has no inversion center and this is in agreement with tetrahedral coordination.…”

Influences of structure and composition on the photoelectrochemical behaviour of anodic films on Zr and Zr–20at.%Ti

“…Ce) and undersized (i.e. Ge, Ti) cations with respect to Zr 4+ stabilize tetragonal zirconia and several mechanisms have been proposed in order to explain such a role [51][52][53][54][55][56][57][58][59]. As a consequence of the structural changes caused by Ti 4+ into the ZrO 2 lattice, several authors [53,[55][56][57] report that a reduction of the free oxygen vacancies occurs in TiO 2 doped zirconia.…”

Relationships between structural and electrical properties in mixed conductors duplex materials in the ZrO2-Y2O3-TiOColomer1, Díaz‐Moreno2, Boada3 et al. 2014Phys. Rev. B

“…Most of the research efforts performed in the past have been mainly focused on the electrical properties of mixed conductors based on titania-doped yttria-stabilized zirconia and on the titania-doped yttria-tetragonal zirconia materials [5][6][7][8][9][10][11][12][13][14]. In addition, studies of the local environment of mobile ionic species, i.e.…”

“…In addition, studies of the local environment of mobile ionic species, i.e. the lattice-oxygen vacancies and vacancy complexes, have been only performed for Tidoped YTZP materials [13] but not for Ti-doped YSZ or Ti-doped YTZP/Ti-doped YSZ duplex materials. Materials based on cubic zirconia have higher conductivity than that of Ti-doped YTZP materials at the operation temperature of a SOFC as was mentioned above, and for that reason they should be deeply studied from a structural point of view.…”

“…Previous x-ray absorption spectroscopy (XAS) studies, performed at the Ti K-edge in Ti-YTZP [13,15] based on the fingerprint analysis of the x-ray absorption near-edge structure (XANES) part of the spectrum, suggested a fivefold coordination of the Ti ions and a subsequent loss of centrosymmetry in the Ti-YTZP tetragonal zirconia crystal lattice. Moreover, the analysis of the extended x-ray absorption fine structure (EXAFS) part of the absorption spectrum performed by Capel et al [15] reported Ti-O distances significantly shorter than the main Zr-O ones, which implies an increase in the anisotropy of the tetragonal layer structure.…”