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Iron Substitution in Soil and Synthetic Anatase

Published online by Cambridge University Press:  28 February 2024

U. Schwertmann
Affiliation:
Lehrstuhl für Bodenkunde, Technische Universität München, D-80350 Freising-Weihenstephan
J. Friedl
Affiliation:
Lehrstuhl für Bodenkunde, Technische Universität München, D-80350 Freising-Weihenstephan
G. Pfab
Affiliation:
Lehrstuhl für Bodenkunde, Technische Universität München, D-80350 Freising-Weihenstephan
A. U. Gehring
Affiliation:
Lehrstuhl für Bodenkunde, Technische Universität München, D-80350 Freising-Weihenstephan

Abstract

IronIII for TiIV 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 FeIII 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 H2O/mol Fe. At 600°C structural Fe was ejected, the unit cell size decreased to that of pure anatase, and pseudobrookite, Fe2TiO5, was formed.

Type
Research Article
Copyright
Copyright © 1995, The Clay Minerals Society

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