Cd-Substituted Goethites — A Structural Investigation by Synchrotron X-ray Diffraction
Authors:
- Trang HuynhTHTrang Huynh
- Andrew R. TongATAndrew R. Tong
- Balwant SinghBalwant Singh
- Brendan J. KennedyBKBrendan J. Kennedy
- 1 August 2003
- journal article
- Published by Cambridge University Press (CUP) in Clays and Clay Minerals
- Vol. 51 (4) , 397-402
Abstract
The structural and physical effects of partially substituting Cd for Fe in goethite have been investigated. The solubility of Cd2+ in goethite is ∼10 mol.%, i.e. Fe0.905Cd0.095OOH. The structures of the substituted goethites have been refined, using the Rietveld method, from synchrotron X-ray powder diffraction data. There is a progressive increase in the size of the unit-cell parameters and unit-cell volume, upon the incorporation of much larger Cd2+ ion (0.95 Å) compared with Fe3+ (0.645 Å) in the goethite structure, together with a reduction in crystallinity. Transmission electron microscopy measurements confirm the crystallite size decreases as the Cd2+ content increases in goethite structure.Keywords
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