X-RAY-DIFFRACTION, INFRARED AND TGA DTG ANALYSIS OF HYDRATED NACRITE/

An homogenous 8.4 Angstrom hydrate was obtained after washing intercal ated KAc-nacrite. X-ray diffraction analysis based on comparison of th e experimental and calculated profiles enabled the amount of water (on e molecule per Si2Al2O5(OH)(4)) and the z coordinate along c (6.5 Ang strom) to be determined. The hydration state was accompanied by a decr ease in the coherent domain along c in the order nacrite > KAc-nacrit e > H2O-nacrite. The IR spectrum of the hydrated nacrite showed an evo lution of the structure with a shift of v(OH) from 3702, 3649 and 3630 cm(-1) to 3690, 3641 and 3620 cm(-1), respectively for the nacrite hy droxyls. The v(OH) stretching bands of the interlayer water appeared a t 3602 and 3545 cm(-1) and their bending band at 1655 cm(-1). The TGA/ DTG analysis of the air-dry hydrated nacrite showed a loss of water at 245 degrees C, the weight loss (1 molecule per Si2Al2O5(OH)(4)) corre sponding to the interlamellar water, in agreement with that determined by XRD.