Proton and deuterium NMR measurements are performed in Na-fluorhectorite powdered samples. The results are compared with NMR data from other 2:1 clays, and with the recent results of molecular simulations, they yield new information about the factors governing the geometry and dynamics of intercalated water in these materials. In the one-water layer regime, two different sites were identified, permitting us to elucidate the structure of interlamellar water. The role of proton exchange appears to be more pronounced in Na−Fht than in Na−vermiculite and is not limited to the 2WL regime. It appears to be promoted by a considerable amount of interlamellar water outside the hydration sphere of the cation.

(7)Li and (1)H nuclear magnetic resonance together with X-ray diffraction measurements in powdered samples and pseudocrystalline films of synthetic fluorhectorite as a function of relative ambient humidity permit to address several aspects of the structure and dynamics of intercalated water molecules. The role of proton exchange as a possibly dominant mechanism of charge transport in the one-water layer regime of hydration is reexamined. The experimental results in Li-fluorhectorite support the result of molecular simulations which predict, for Li-montmorillonite, the existence of an intermediate regime, between one-water layer and two-water layer states.

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