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The Influence of Aluminum on Iron Oxides. XV. Al-for-Fe Substitution in Synthetic Lepidocrocite

Published online by Cambridge University Press:  02 April 2024

Udo Schwertmann  and
Emilia Wolska
Udo Schwertmann
Affiliation:
Lehrstuhl für Bodenkunde, Technische Universität München, 8050 Freising-Weihenstephan, Federal Republic of Germany
Emilia Wolska
Affiliation:
Adam Mickiewicz Universität, Grunwaldska 6, 60780 Poznan, Poland
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Abstract

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Lepidocrocite samples, γ-FeOOH, containing 0–10 mole % Al-for-Fe substitution were synthesized at 15°C and pH 8 by oxidizing mixed FeCl2-AlCl3 solutions. The unit-cell parameters a, b, and c were measured from step-counted X-ray powder diffractograms using seven lines and Si as an internal standard. With increasing Al substitution from 0 to 10 mole % the unit-cell edge lengths a, b, and c decreased regularly by 0.3, 0.8, and 0.6%, respectively. Furthermore, the crystals became smaller, but gained in thermal stability. Decrease in crystal size parallel to the y axis led to a significant increase of the OH-stretch vibration and a decrease of the out-of-plane OH-bending vibration due to a weakening of the hydrogen bond between the zig-zag layers in the structure.

Keywords

AluminumInfrared spectroscopyIronLepidocrociteX-ray powder diffraction
Type
Research Article
Information
Clays and Clay Minerals , Volume 38 , Issue 2 , April 1990 , pp. 209 - 212
Copyright
Copyright © 1990, The Clay Minerals Society

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