Clays and Clay Minerals, Vol. 57, No. 1, 46–53, 2009.
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Authors
Cabello, E.
Morales, M. P.
Serna, C. J.
Barron, V.
Torrent, J.
Issue Date
2009
Type
Article
Language
Keywords
Periodicals , Geology , Crystallization , Ferrihydrite , Ferrimagnetism , Hematite , Maghemite
Alternative Title
Magnetic Enhancement During The Crystallization Of Ferrihydrite At 25 And 50ºc
Abstract
Abstract—Soil formation usually results in an increase in magnetic susceptibility. The magnetic properties of the products of transformation of ferrihydrite, a typical precursor of other soil Fe oxides, were examined in the present work. Synthetic 2-line ferrihydrite was aged at two temperatures (25 and 50ºC) and two different relative humidities (80 and 100%) in the presence of silicate, phosphate, citrate, and tartrate as adsorbed ligands (molar anion/Fe ratio = 1 3%). The ligands delayed or prevented the transformation of ferrihydrite to hematite. The magnetic susceptibility of the ferrihydrite transformation products increased with aging, the rate of increasede pending on the type of ligand added and its concentration. Thelarge st increase in magnetic susceptibility, sixfold, was obtained with ferrihydrite in a citrate/Fe ratio of 1%, after 1500 days. The resulting magnetic products exihibited superparamagnetic behavior at room temperature and high coercivity at 5 K. The formation of an intermediate ferrimagnetic phase in the ferrihydrite-tohematite transformation might explain the magnetic enhancement observed in many aerobic soils lacking other sources of magnetic minerals.
Description
gsccm57105-cab.pdf 483KB
Citation
Clays and Clay Minerals, Vol. 57, No. 1, 46–53, 2009.
Publisher
The Clay Minerals Society
License
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