FT-RAMAN SPECTROSCOPY OF THE LATTICE REGION OF KAOLINITE AND ITS INTERCALATES

The structure of a highly ordered kaolinite from Kiralyhegy, Hungary, and an ordered halloysite from Szeg, Hungary, together with their urea and potassium acetate intercalates, have been studied using FT-Raman spectroscopy. Remarkable changes in the Raman spectra after intercalat ion of the kaolinites with urea or potassium acetate, in the lattice r egion of the kaolinite, were observed over the spectral range 150 to 1 000 cm(-1). In particular, for the potassium acetate intercalates, the 144 (Szeg) and 915 cm(-1) (Kiralyhegy) bands increased by an order of magnitude and were found to be polarised with a depolarisation ratios of ca. 0.47. Decreases in intensity of the bands at 245, 274 and 334 cm(-1) were observed upon intercalation. Changes in the Raman spectra of both the urea and potassium acetate intercalating molecules upon in tercalation, form the basis of molecular models for the intercalation process.