Hostname: page-component-cd9895bd7-gbm5v Total loading time: 0 Render date: 2024-12-23T12:19:17.039Z Has data issue: false hasContentIssue false
  • English
  • Français

hk-Ordering in Aluminous Nontronite and Saponite Synthesized Near 90°C: Effects of Synthesis Conditions on Nontronite Composition and Ordering

Published online by Cambridge University Press:  28 February 2024

V. C. Farmer ,
W. J. McHardy ,
F. Elsass  and
M. Robert
V. C. Farmer
Affiliation:
The Macaulay Land Use Research Institute, Craigiebuckler, Aberdeen AB9 2QJ, United Kingdom
W. J. McHardy
Affiliation:
Station de Science du Sol INRA, Route de Saint-Cyr, 78026 Versailles, France
F. Elsass
Affiliation:
Station de Science du Sol INRA, Route de Saint-Cyr, 78026 Versailles, France
M. Robert
Affiliation:
Station de Science du Sol INRA, Route de Saint-Cyr, 78026 Versailles, France
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

In studies on the fate of aluminium in the environment, nontronite and saponite have been obtained by synthesis in reducing alkaline conditions close to those prevailing in poorly drained soils developed from limestones. The two minerals obtained have different structures and organizations corresponding to two different growth and/or maturation mechanisms. High-resolution transmission electron microscopy of ultrathin sections of a synthetic aluminous nontronite embedded in resin showed the presence of crystallites consisting of two to ten co-terminating parallel layers, indicating synchronous growth. Electron diffraction showed that the individual crystallites had hk-ordering, i.e., orientation of layers with respect to the six-fold pseudosymmetry of the unit cell. Deposits of a synthetic saponite included hk-ordered crystallites and crinkled films with turbostratic stacking. The two saponite phases had slightly different b dimensions. Lattice fringe images of sections of saponite embedded in resin showed a high angular disorientation of the layers in the stacking direction, suggesting multiple nucleation and growth of individual layers, subsequently aggregated with imperfect parallelism.

Exploration of the synthetic conditions of the aluminous nontronite indicated that calcium was essential for an hk-ordered product. Syntheses using potassium or sodium hydroxides and carbonates for pH control gave poorly organized nontronites. Hydrazine was not essential for nontronite formation, but better crystallized products—judging by their IR spectra—were obtained in its presence by maintaining reducing conditions in the early stages of synthesis. Attempts to prepare ferruginous beidellites under similar conditions to those in which aluminous nontronites formed were unsuccessful.

Keywords

BeidelliteElectron diffractionHigh-resolution electron microscopyhk-orderLattice imagingLayer stackingNontroniteNontronite synthesisSaponite
Type
Research Article
Information
Clays and Clay Minerals , Volume 42 , Issue 2 , April 1994 , pp. 180 - 186
Copyright
Copyright © 1994, Clay Minerals Society

References

Borchardt, G., (1989) Smectites: in Minerals in Soil Environments: 2nd ed., J. B. Dixon and S. B. Weed, eds., Soil Science Society of America, Madison, 675–727.Google Scholar
Farmer, V. C., (1992) Possible confusion between so-called ferrihydrites and hisingerites: Clay Miner. 27, 373–378.CrossRefGoogle Scholar
Farmer, V. C., Krishnamurti, G. S. R., and Huang, P. M., (1991b) Synthetic-allophane and layer-silicate formation in SiO2-Al2O3-FeO-Fe2O3-MgO-H2O systems at 23°C and 89°C in a calcareous environment: Clays & Clay Minerals 39, 561–570.CrossRefGoogle Scholar
Farmer, V. C., McHardy, W. J., Palmieri, F., Violante, A., and Violante, P., (1991a) Synthetic allophanes formed in calcareous environments: Nature, conditions of formation, and transformations: Soil Sci. Soc. Am. J. 55, 1162–1166.CrossRefGoogle Scholar
Farmer, V. C., and Russell, J. D., (1990) Structures and genesis of allophanes and imogolite, and their distribution in non-volcanic soils: in Soil Colloids and their Association in Aggregates, de Boodt, M. F., Hayes, M. H. B., and Herbillon, A., eds., Plenum Press, New York, 165–178.CrossRefGoogle Scholar
Nadeau, P. H., and Tait, J. M., (1987) Transmission electron microscopy: in A Handbook of Determinative Methods in Clay Mineralogy, Wilson, M. J., ed., Blackie, Glasgow and London, 209–247.Google Scholar
Paterson, E., Goodman, B. A., and Farmer, V. C., (1991) The chemistry of aluminium, iron and manganese oxides in acid soils: in Soil Acidity, Ulrich, B., and Sumner, M. E., eds., Springer-Verlag, Heidelberg, 97–124.CrossRefGoogle Scholar
Srodón, J., Andreoli, C., Elsass, F., and Robert, M., (1990) Direct high-resolution transmission electron microscopic measurement of expandability of mixed-layer illite/smectite in bentonite rock: Clays & Clay Minerals 38, 373–379.CrossRefGoogle Scholar
Tessier, D., and Pedro, G., (1987) Mineralogical characterization of 2: 1 clays in soils: Importance of the clay texture: in Proceedings of the International Clay Conference, Denver, 1985, Schultz, L. G., Olphen, H. van, and Mumpton, F. A., eds., The Clay Minerals Society, Bloomington, Indiana, 78–84.Google Scholar
Velde, B., (1985) Clay Minerals: A Physico-chemical Explanation of Their Occurrence. Elsevier, Amsterdam , 427 pp.Google Scholar
Wada, K., (1989) Allophane and imogolite: in Minerals in Soil Environments: 2nd ed., J. B. Dixon and S. B. Weed, eds., Soil Science Society of America, Madison, Wisconsin, 603–638.Google Scholar
Wilson, M. J., (1987) Soil smectites and related interstratified minerals: Recent developments: in Proceedings of the International Clay Conference, Denver, 1985, Schultz, L. G., Olphen, H. van, and Mumpton, F. A., eds., The Clay Minerals Society, Bloomington, Indiana, 167–173.Google Scholar