Iron Substitution in Soil and Synthetic Anatase

Abstract

Abstract Iron III for Ti IV substitution in the structure of pedogenic and synthetic anatase of up to Fe/ (Ti+Fe) 0.1 mol/mol was indicated by an increase in unit cell size as measured by XRD line shifts. Mössbauer- and electron paramagnetic resonance spectra at both, 298 K and 4.2 K supported this by the presence of signals typical for octahedrally coordinated Fe III in a diamagnetic matrix. Charge compensation was achieved by structural OH, as indicated by FTIR bands at 3360 and 960 cm −1 , which were absent in pure anatase and which disappeared on heating. The weight loss on heating amounted to ca. 0.5 mol H 2 O/mol Fe. At 600°C structural Fe was ejected, the unit cell size decreased to that of pure anatase, and pseudobrookite, Fe 2 TiO 5 , was formed.