XAS spectra of mechanically milled TiO₂

Characterization and x-ray absorption spectroscopy of ilmenite nanoparticles derived from natural ilmenite ore via acid-assisted mechanical ball-milling process

“…Figure 5(b) shows the corresponding firstorder derivative XAS. The spectra of Ti near-edge region and white lines shown in figure 5 can be ascribed to the electron transition from 1s orbital to 4p orbital in continuum states [24,[26][27][28][29][30]. Ti K-edge absorption energy of the ilmenite phase (ilmenite standard and ilmenite ore) is 4977 eV [31] apparently at lower energy than rutile TiO 2 reference due to the presence of Fe-O-Ti linkage of FeTiO 3 [32,33] and contribution of Fe 2 TiO 4 phase [34].…”

“…Figure 6 exhibits the Ti pre-edge region of the distorted octahedral crystal field assigned to the transition of energy from 1s to 3d transition hybridized with 4p and the 4p-4s hybridization [24,25,39]. The pre-edge of Ti 3d splits into the three fold t 2g state with lower energy (A) and at the higher energy of two fold e g orbital (B) due to the ligand field of distorted octahedral TiO 6 cluster [27].…”

“…The acid-induced dissolution behaviour of ilmenite typically correlates to local structure at particle surface such as surface terminal texture of crystal structure, structural disorder, lattice stress and strain induced by mechanical milling activation. The change in local structure of titanate during ball-milling process is important especially in part of amorphous phase that could be evaluated by x-ray absorption near edge spectroscopy (XANES) study [24,25]. However, based on our recent knowledge, the local structure evolution on ball-milled ilmenite ore has been rarely reported.…”