X-ray diffraction, infrared and TGA/DTG analysis of hydrated nacrite

An homogenous 8.4 Å hydrate was obtained after washing intercalated KAc- nacrite. X-ray diffraction analysis based on comparison of the experimental and calculated profiles enabled the amount of water (one molecule per Si2Al2O5(OH)4) and the z coordinate along c* (6.5 Å) to be determined. The hydration state was accompanied by a decrease in the coherent domain along c* in the order nacrite > KAc-nacrite > H2O-nacrite. The IR spectrum of the hydrated nacrite showed an evolution of the structure with a shift of ν(OH) from 3702, 3649 and 3630 cm−1 to 3690, 3641 and 3620 cm−1, respectively for the nacrite hydroxyls. The ν(OH) stretching bands of the interlayer water appeared at 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°C the weight loss (1 molecule per Si2Al2O5(OH)4) corresponding to the interlamellar water, in agreement with that determined by XRD.