Determination of phase ratio in polymorphic materials by x-ray absorption spectroscopy: The case of anatase and rutile phase mixture in TiO2

Abstract

We demonstrate that x-ray absorption spectroscopy ͑XAS͒ can be used as an unconventional characterization technique to determine the proportions of different crystal phases in polymorphic samples. As an example, we show that ratios of anatase and rutile phases contained in the TiO 2 samples obtained by XAS are in agreement with conventional x-ray diffraction ͑XRD͒ measurements to within a few percent. We suggest that XAS measurement is a useful and reliable technique that can be applied to study the phase composition of highly disordered or nanoparticle polymorphic materials, where traditional XRD technique might be difficult.

Spectroscopic evidence of NOx formation and band-gap narrowing in N-doped TiO2 films grown by pulsed magnetron sputtering

“…Moreover, XANES presents an energy resolution of w0.1 eV, being able to resolve very fine spectral features and the analysis can be expanded to larger depths than in XPS (up to a few tens of nanometers). In the case of TiO 2 , distinct XANES spectral features for each atomic structure can be used for phase identification [19] and quantification [20]. Due to its local-order character, XANES has been applied to study TiO 2 in the form of aerogels and nanometer-sized powders [21,22], as well as to analyze the bonding structure [23,24] and evolution upon annealing [25] of amorphous films.…”

Surface Morphology of Heterogeneous Nanocrystalline Rutile/Amorphous Anatase TiO2 Films Grown by Reactive Pulsed Magnetron Sputtering

“…TMOs have been extensively studied by XANES, where distinct spectral features for each atomic structure can be used as phase fingerprints 9, 10. In this way, XANES has been used to determine quantitatively the phase ratio in mixed polymorphic materials using the example of TiO 2 11. Due to its suitability to study samples with low degree of structural order, XANES has also been extended to amorphous TiO 2 in the form of aerogels and nanometer‐sized powders,12, 13 as well as to amorphous or highly disordered films 14–16…”