Heterogeneity in iron-doped titania flower-like nanocrystalline aggregates: detection of brookite and anatase/rutile size-strain modeling

Detailed investigations of Raman spectra and X-ray powder diffraction (XRPD) patterns of rutile-rich and anatase/brookite-poor flower-like nanocrystalline aggregates of Fe-doped TiO₂ shed new light with regard to its microstructure and heterogeneity. The brookite phase has been detected from the Raman spectra, and the presence of different phases in pure and doped samples is discussed. The phonon confinement model (PCM) was applied to Raman spectra, and the Warren-Averbach and simplified integral breadth methods were applied to XRPD patterns in order to obtain information about the nanocrystallite size and strain of rutile and anatase. The applied methods (i.e. XRPD size-strain analysis and the PCM fit of Raman spectra), when used in combination and together with other experimental techniques like high-resolution transmission electron microscopy, could be very useful in nanomaterial characterization.