Order and Disorder Relations in the Distribution of the Substitutions in Smectites, Illites and Vermiculites

G. Besson, A. Mifsud, C. Tchoubar and J. Mering
Centre de Recherche sur les Solides à Organisation Cristalline Imparfaite, Orleans, Laboratoire de Cristallographie, Université d'Orleans, France

Abstract: It is shown that order-disorder relations in the distribution of the isomorphous substitutions are important in the characterization of different 2/1 phyllosilicates and in the determination of their behavior. These order-disorder relations are shown by selected area diffraction patterns obtained from single crystals. The range of layer charges corresponding to smectites (charge per half-cell <0.6) is that for which phyllosilicates are stable with disordered substitutions. Phyllites with charge >0.6 show anomalous diffusions which indicate that the distributions of exchangeable Ba ions are partially ordered; this result is taken as evidence that the isomorphous substitutions also are partially ordered.

Clays and Clay Minerals; December 1974 v. 22; no. 5–6; p. 379-384; DOI: 10.1346/CCMN.1974.0220503
© 1974, The Clay Minerals Society
Clay Minerals Society (www.clays.org)