TiK-edge XANES studies of Ti coordination and disorder in oxide compounds: Comparison between theory and experiment

Structural refinement and photoluminescence properties of irregular cube-like (Ca1−xCux)TiO3 microcrystals synthesized by the microwave–hydrothermal method

“…This forbidden electronic dipole transition is normally allowed by the mixture of p orbitals from surrounding oxygen atoms into the unfilled d states of titanium atoms [39]. Farges et al [40] have reported that the intensity and energy of this peak in titanates is associated with the coordination number of the Ti atoms (4, 5, and 6) with the oxygen atoms. As can be seen at Fig.…”

Combination of XANES spectroscopy and molecular dynamics to probe the local structure in disordered systems

“…Usually, the latter has been achieved by building clusters of growing size using crystallographic parameters, quantum-chemical optimizations, or a variety of other strategies. [6][7][8] But shells beyond the first one are not accounted for realistically in systems without long-range order. On the other hand, discrepancies can be due to some of the approximations in the quantumchemical calculations such as the use of muffin-tin potentials, self-energy approximations, self-consistency, .…”

Pre-edge structure analysis of Ti K-edge polarized X-ray absorption spectra in TiO2 by full-potential XANES calculations

“…The understanding of the chemical and electronic properties of titanium oxides is of great interest in catalysis, geological sciences, and high-To superconductivity (Kung, 1989;Farges et al, 1997, Durmeyer et al, 1990. Core level spectroscopies are known to be a good tool for such purposes and have been exploited for various titanium oxides Wu et al, 1997 and references therein).…”

“…Although its electronic structure is now assumed to be well-known (Hardman et al, 1994;Sorantin & Schwarz, 1992;Glassford & Chelikowsky, 1992;Khan et al, 1991;Poumellec et al, 1991b), there is still a doubt about the interpretation of its x-ray absorption pre-edge structure at the Ti A'-edge, which is composed of three well defined features (usually labelled Al, A2 and A3). Indeed the pre-edge region is the subject of a large debate not closed yet: in section V-E, Farges et al (1997) recall the recent studies of the pre-edge structure. All the cited interpretations are made from the isotropic spectrum, for which the agreement between theory and experiment is quite satislying (Ruiz-Lbpez & Mufioz-P~iez, 1991;Poumellec et aL, 1991 b;Wu et al, 1997).…”