Experimental Structure Factor Curves of Montmorillonites

Abstract

Diffraction from oriented flakes of four montmorillonites that had been treated with an excess of four glycols was obtained. Peak areas for the 00l diffraction from each of the treated clays were plotted against sin θ/λ.

It was assumed that the observed diffraction intensity for the complexes was equal to that of the clay plus or minus that of the organic part of the complex. By assuming also that the contribution from the organic part of the complex is the same for each clay at any one value of sin θ/λ, a systematic consideration of all the possible levels of contribution by the organic interlayer material could be made. At values of sin θ/λ where intensity data were closely spaced, it was found that only one of the possible levels of contribution by the organic interlayer material would allow a residual intensity (attributable to the clay) that fit on smooth curves.

Curves of the diffraction intensity attributable to each of the clays resembled, in their gross features, the calculated structure factor curve of mica. Displacements of the nodes along the sin θ/λ axis and differences in loop heights are sufficient to make this experimental structure factor curve for each of the five clays quite distinctive.