Dosage quantitatif des kaolinites et des illites par diffraction de rayons X

Abstract

Orientation effects and structural disorder have prevented a quantitative X-ray analysis of clay minerals. Orientation control is possible by compaction of material after mixing with an orientable standard : molybdenite. This analysis uses the 001 reflection whose the features height H and half-height width I are measured with reference to the standard reflection. This peak area S is given by S = H x I. A first type of disorder has the particularity to be increased by grinding. The 001 reflection behaviour during grinding is : S = Sc x H[power]0.86 where S is the relative peak area, H the height and Sc the corrected area, free of this type of disorder. A second type of disorder is pointed out by the broadening of 001 peak according to Sc = Si x I[power]0.6 where I is the half-height width. Si, the intrinsic area, is free of disorder degree and only dependent of the amount of mineral in the material. By the use of this intrinsic area for the quantitative analysis of material with kaolinite and illite of various degrees of disorder, good results can be gained.