Hostname: page-component-cd9895bd7-jkksz Total loading time: 0 Render date: 2024-12-24T23:57:27.500Z Has data issue: false hasContentIssue false
  • English
  • Français

The influence of aluminium on iron oxides: XIII. Properties of goethites synthesised in 0·3 M KOH at 25°C

Published online by Cambridge University Press:  09 July 2018

D. G. Schulze  and
U. Schwertmann
D. G. Schulze
Affiliation:
Agronomy Department, Purdue University, West Lafayette, Indiana 47907, USA
U. Schwertmann
Affiliation:
Institut für Bodenkunde, Technische Universität München, 8050 Freising-Weihenstephan, FRG
Get access Rights & Permissions [Opens in a new window]

Abstract

Aluminium-substituted goethites were synthesised in 0·3 M KOH at either 25° or 70°C. The 25°C goethites had unit-cell a and c dimensions about 0·1–0·2% larger than the 70°C goethites of comparable Al substitution. Unit-cell b dimensions were similar regardless of synthesis temperature. The 25°C goethites contained larger amounts of Al in their structures than the 70°C goethites synthesised at the same initial Al/(Al + Fe) mole ratio in solution. The 25°C goethites had lower dehydroxylation temperatures and smaller differences between the two OH-bending bands than comparable 70°C goethites. These differences between the two sets of goethites are believed to be caused by the presence of more structural defects in the 25°C goethites than in the 70°C goethites. Goethites with the lowest Al substitutions consisted of crystals with several coherently diffracting domains, while at high Al substitutions the crystals were mainly monodomainic. Surface areas of the 25°C goethites varied in a complex manner as a function of thickness along [100], character of the domains, and physical size.

Type
Research Article
Information
Clay Minerals , Volume 22 , Issue 1 , March 1987 , pp. 83 - 92
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1987

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Cornell, R.M., Mann, S. & Skarnulis, A.J. (1983) A high-resolution electron microscopy examination of domain boundaries in crystals of synthetic goethite. J. Chem. Soc., Faraday Trans. 1 79, 2679–2684.Google Scholar
Fey, M.V. & Dixon, J.B. (1981) Synthesis and properties of poorly crystalline hydrated aluminous goethites. Clays Clay Miner. 29, 91–100.Google Scholar
Goodman, B.A. & Lewis, D.G. (1981) Mössbauer spectra of aluminous goethites (α-FeOOH). J. Soil Sci. 32, 351–363.CrossRefGoogle Scholar
Klug, H.P. & Alexander, L.E. (1974) X-ray Diffraction Procedures for Polycrystalline and Amorphous Materials. Wiley, New York, 966 pp.Google Scholar
Koutler-Anderson, E. (1953) The sulfosalicylic acid method for iron determinations and its use in certain soil analyses. Ann. Roy. Agric. Coll. Sweden 20, 297–308.Google Scholar
Lewis, D.G. & Schwertmann, U. (1979a) The influence of Al on iron oxides: Part III. Preparation of Al goethites in M KOH. Clay Miner. 14, 115–126.Google Scholar
Lewis, D.G. & Schwertmann, U. (1979b) The influence of aluminum on the formation of iron oxides: IV. The influence of [Al], [OH], and temperature. Clays Clay Miner. 27, 195–200.Google Scholar
Schulze, D.G. (1984) The influence of aluminum on iron oxides: VII. Unit cell dimensions of Al-substituted goethites and estimation of Al from them. Clays Clay Miner. 32, 3644.Google Scholar
Schulze, D.G. (1981) Identification of soil iron oxide minerals by differential X-ray diffraction. Soil Sci. Soc. Am. J. 45, 437–440.CrossRefGoogle Scholar
Schulze, D.G. & Schwertmann, U. (1984) The influence of aluminium on iron oxides: X. Properties of Al- substituted goethites. Clay Miner. 19, 521–539.CrossRefGoogle Scholar
Schwertmann, U. (1964). Differenzierung der Eisenoxide des Bodens durch Extraktion mit Ammoniumoxalat-Lösung. Z. Pflanzenern. Düng. Bodenkunde 105, 194–202.Google Scholar
Schwertmann, U., Cambier, P. & Murad, E. (1985) Properties of goethites of varying crystallinity. Clays Clay Miner. 33, 369–378.CrossRefGoogle Scholar
Schwertmann, U. & Kämpf, N. (1985) Properties of goethite and hematite in kaolinitic soils of southern and central Brazil. Soil Sci. 139, 344–350.Google Scholar
Schwertmann, U. & Taylor, R.M. (1986) Iron oxides: in Minerals in Soil Environments, 2nd ed. (Dixon, J. B. & Weed, S. B., editors). Soil Sci. Soc. Am., Madison, Wisconsin (in press).Google Scholar