Abstract
AbstractThe water dynamics in Na3PMo12O40·nH2O and Na3PMo12O40·nD2O with different n was studied by 1H, 2H, and 23Na NMR spectra and relaxation time measurements over a wide temperature range. The water molecules in hydrate with n = 29 and deuterated hydrate with n = 20 behave like those in bulk water at room temperature. Below room temperature four phase transitions occur in these substances and the degrees of motional freedom of water molecules are lost successively on cooling through the transition points. The mode of the water motions in each phase was assigned by the spectral and the relaxation data analysis: The activation energies for the water motions are 25.9 kJ mol−1 for isotropic rotation and 12.4 kJ mol−1 for translational diffusion in hydrate with n = 29. In the hexahydrate and deuterated hexahydrate only a restricted motion occurs below room temperature down to 120 K, suggesting that the water molecules are far separated from each other and there is no significant interaction between them.
Published Version
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